Update .gitlab-ci.yml to use anchors for all VisualStudio jobs and the linux tags.

* reduces filesizes and improves maintainability

.gitlab-ci.yml

-gcc-c++11:
-  script: "CI/ci-linux.sh gcc C++11"
-  tags:
-    - Linux
-
-clang-c++11:
-  script: "CI/ci-linux.sh clang C++11"
+### Templates for common job definitions ###
+.LINUX_TAG: &LINUX_TAG
   tags:
     - Linux
 
-gcc-c++14:
-  script: "CI/ci-linux.sh gcc C++14"
-  tags:
-    - Linux
-
-clang-c++14:
-  script: "CI/ci-linux.sh clang C++14"
-  tags: 
-    - Linux
-
-macos-c++11:
-  script: "CI/ci-mac.sh C++11"
-  tags:
-    - Apple
-  artifacts:
-    paths:
-      - build-release-cpp11/*.dmg
-      - build-release-cpp11/*.tar.gz
-
-macos-c++98:
-  script: "CI/ci-mac.sh C++14"
-  tags:
-    - Apple
-  artifacts:
-    paths:
-      - build-release-cpp14/*.dmg
-      - build-release-cpp14/*.tar.gz
-
-cppcheck:
-  script: "CI/ci-cppcheck.sh"
-  tags:
-    - Linux
-  artifacts:
-    paths:
-      - cppcheck.log
+### VS2017 ###
 
 .VS2017_64_TEMPLATE: &VS2017_x64
   variables:
@@ -55,41 +16,11 @@ cppcheck:
   tags:
     - VS2017
     - Qt5101
-      
-VS2017-64-bit-shared-apps:
-  variables:
-    SHARED:         "TRUE"
-    APPS:           "ON"
-  <<: *VS2017_x64
-  
-      
-VS2017-64-bit-static-apps:
-  variables:
-    SHARED:         "FALSE"
-    APPS:           "ON"
-  <<: *VS2017_x64
-
-      
-VS2017-64-bit-shared-no-apps:
-  variables:
-    SHARED:         "TRUE"
-    APPS:           "OFF"
-  <<: *VS2017_x64
-
 
-VS2017-64-bit-static-no-apps:
-  variables:
-    SHARED:         "FALSE"
-    APPS:           "OFF"
-  <<: *VS2017_x64
-
-
-VS2017-32-bit-shared-no-apps:
+.VS2017_32_TEMPLATE: &VS2017_x32
   variables:
     BUILD_PLATFORM: "VS2017"
     ARCHITECTURE:   "x32"
-    SHARED:         "TRUE"
-    APPS:           "OFF"
   script: "CI\\Windows.bat"
   tags:
     - VS2017
@@ -97,40 +28,12 @@ VS2017-32-bit-shared-no-apps:
     paths:
       - build-release/*.exe
 
+### VS2015 ###
 
-VS2017-32-bit-static-no-apps:
-  variables:
-    BUILD_PLATFORM: "VS2017"
-    ARCHITECTURE:   "x32"
-    SHARED:         "FALSE"
-    APPS:           "OFF"
-  script: "CI\\Windows.bat"
-  tags:
-    - VS2017
-  artifacts:
-    paths:
-      - build-release/*.exe
-
-VS2015-64-bit-shared-apps:
-  variables:
-    BUILD_PLATFORM: "VS2015"
-    ARCHITECTURE:   "x64"
-    SHARED:         "TRUE"
-    APPS:           "ON"
-  script: "CI\\Windows.bat"
-  tags:
-    - VS2015
-  artifacts:
-    paths:
-      - build-release/*.exe
-      
-      
-VS2015-64-bit-shared-no-apps:
+.VS2015_64_TEMPLATE: &VS2015_x64
   variables:
     BUILD_PLATFORM: "VS2015"
     ARCHITECTURE:   "x64"
-    SHARED:         "TRUE"
-    APPS:           "OFF"
   script: "CI\\Windows.bat"
   tags:
     - VS2015
@@ -138,12 +41,10 @@ VS2015-64-bit-shared-no-apps:
     paths:
       - build-release/*.exe
 
-VS2015-32-bit-shared-apps:
+.VS2015_32_TEMPLATE: &VS2015_x32
   variables:
     BUILD_PLATFORM: "VS2015"
     ARCHITECTURE:   "x32"
-    SHARED:         "TRUE"
-    APPS:           "ON"
   script: "CI\\Windows.bat"
   tags:
     - VS2015
@@ -151,176 +52,183 @@ VS2015-32-bit-shared-apps:
     paths:
       - build-release/*.exe
 
-VS2015-32-bit-shared-no-apps:
-  variables:
-    BUILD_PLATFORM: "VS2015"
-    ARCHITECTURE:   "x32"
-    SHARED:         "TRUE"
-    APPS:           "OFF"
-  script: "CI\\Windows.bat"
-  tags:
-    - VS2015
-  artifacts:
-    paths:
-      - build-release/*.exe
-      
-VS2015-64-bit-static-apps:
-  variables:
-    BUILD_PLATFORM: "VS2015"
-    ARCHITECTURE:   "x64"
-    SHARED:         "FALSE"
-    APPS:           "ON"
-  script: "CI\\Windows.bat"
-  tags:
-    - VS2015
-  artifacts:
-    paths:
-      - build-release/*.exe
+### VS2013 ###
 
-VS2015-64-bit-static-no-apps:
+.VS2013_64_TEMPLATE: &VS2013_x64
   variables:
-    BUILD_PLATFORM: "VS2015"
+    BUILD_PLATFORM: "VS2013"
     ARCHITECTURE:   "x64"
-    SHARED:         "FALSE"
-    APPS:           "OFF"
   script: "CI\\Windows.bat"
   tags:
-    - VS2015
+    - VS2013
   artifacts:
     paths:
       - build-release/*.exe
 
-VS2015-32-bit-static-apps:
+.VS2013_32_TEMPLATE: &VS2013_x32
   variables:
-    BUILD_PLATFORM: "VS2015"
+    BUILD_PLATFORM: "VS2013"
     ARCHITECTURE:   "x32"
-    SHARED:         "FALSE"
-    APPS:           "ON"
   script: "CI\\Windows.bat"
   tags:
-    - VS2015
+    - VS2013
   artifacts:
     paths:
       - build-release/*.exe
 
-VS2015-32-bit-static-no-apps:
+### Linker and App configurations for VS ###
+
+.STATIC_NO_APPS: &STATIC_NO_APPS
   variables:
-    BUILD_PLATFORM: "VS2015"
-    ARCHITECTURE:   "x32"
     SHARED:         "FALSE"
     APPS:           "OFF"
-  script: "CI\\Windows.bat"
-  tags:
-    - VS2015
-  artifacts:
-    paths:
-      - build-release/*.exe
-      
-      
-      
-VS2013-64-bit-shared-apps:
+    
+.STATIC_APPS: &STATIC_APPS
   variables:
-    BUILD_PLATFORM: "VS2013"
-    ARCHITECTURE:   "x64"
-    SHARED:         "TRUE"
+    SHARED:         "FLASE"
     APPS:           "ON"
-  script: "CI\\Windows.bat"
-  tags:
-    - VS2013
-  artifacts:
-    paths:
-      - build-release/*.exe
-
-VS2013-64-bit-shared-no-apps:
+    
+.SHARED_NO_APPS: &SHARED_NO_APPS
   variables:
-    BUILD_PLATFORM: "VS2013"
-    ARCHITECTURE:   "x64"
     SHARED:         "TRUE"
     APPS:           "OFF"
-  script: "CI\\Windows.bat"
-  tags:
-    - VS2013
-  artifacts:
-    paths:
-      - build-release/*.exe
 
-VS2013-32-bit-shared-apps:
+.SHARED_APPS: &SHARED_APPS
   variables:
-    BUILD_PLATFORM: "VS2013"
-    ARCHITECTURE:   "x32"
     SHARED:         "TRUE"
     APPS:           "ON"
-  script: "CI\\Windows.bat"
+ 
+### actual job definitions ###
+
+gcc-c++11:
+  script: "CI/ci-linux.sh gcc C++11"
+  <<: *LINUX_TAG
+
+clang-c++11:
+  script: "CI/ci-linux.sh clang C++11"
+  <<: *LINUX_TAG
+
+gcc-c++14:
+  script: "CI/ci-linux.sh gcc C++14"
+  <<: *LINUX_TAG
+
+clang-c++14:
+  script: "CI/ci-linux.sh clang C++14"
+  <<: *LINUX_TAG
+
+macos-c++11:
+  script: "CI/ci-mac.sh C++11"
   tags:
-    - VS2013
+    - Apple
   artifacts:
     paths:
-      - build-release/*.exe
+      - build-release-cpp11/*.dmg
+      - build-release-cpp11/*.tar.gz
 
-VS2013-32-bit-shared-no-apps:
-  variables:
-    BUILD_PLATFORM: "VS2013"
-    ARCHITECTURE:   "x32"
-    SHARED:         "TRUE"
-    APPS:           "OFF"
-  script: "CI\\Windows.bat"
+macos-c++98:
+  script: "CI/ci-mac.sh C++14"
   tags:
-    - VS2013
+    - Apple
   artifacts:
     paths:
-      - build-release/*.exe
-      
-VS2013-64-bit-static-apps:
-  variables:
-    BUILD_PLATFORM: "VS2013"
-    ARCHITECTURE:   "x64"
-    SHARED:         "FALSE"
-    APPS:           "ON"
-  script: "CI\\Windows.bat"
+      - build-release-cpp14/*.dmg
+      - build-release-cpp14/*.tar.gz
+
+cppcheck:
+  script: "CI/ci-cppcheck.sh"
   tags:
-    - VS2013
+    - Linux
   artifacts:
     paths:
-      - build-release/*.exe
+      - cppcheck.log
+
+VS2017-64-bit-shared-apps:
+  variables: *SHARED_APPS
+  <<: *VS2017_x64
+  
+VS2017-64-bit-static-apps:
+  variables: *STATIC_APPS
+  <<: *VS2017_x64
+
+VS2017-64-bit-shared-no-apps:
+  variables: *SHARED_NO_APPS
+  <<: *VS2017_x64
+
+VS2017-64-bit-static-no-apps:
+  variables: *STATIC_NO_APPS
+  <<: *VS2017_x64
+
+VS2017-32-bit-shared-no-apps:
+  variables: *SHARED_NO_APPS
+  <<: *VS2017_x32
+
+VS2017-32-bit-static-no-apps:
+  variables: *STATIC_NO_APPS
+  <<: *VS2017_x32
+
+VS2015-64-bit-shared-apps:
+  variables: *SHARED_APPS
+  <<: *VS2015_x64
+
+VS2015-64-bit-shared-no-apps:
+  variables: *SHARED_NO_APPS
+  <<: *VS2015_x64
+
+VS2015-64-bit-static-apps:
+  variables: *STATIC_APPS
+  <<: *VS2015_x64
+
+VS2015-64-bit-static-no-apps:
+  variables: *STATIC_NO_APPS
+  <<: *VS2015_x64
+
+VS2015-32-bit-shared-apps:
+  variables: *SHARED_APPS
+  <<: *VS2015_x32
+
+VS2015-32-bit-shared-no-apps:
+  variables: *SHARED_NO_APPS
+  <<: *VS2015_x32
+
+VS2015-32-bit-static-apps:
+  variables: *STATIC_APPS
+  <<: *VS2015_x32
+
+VS2015-32-bit-static-no-apps:
+  variables: *STATIC_NO_APPS
+  <<: *VS2015_x32
+
+VS2013-64-bit-shared-apps:
+  variables: *SHARED_APPS
+  <<: *VS2013_x64
+
+VS2013-64-bit-shared-no-apps:
+  variables: *SHARED_NO_APPS
+  <<: *VS2013_x64
+
+VS2013-64-bit-static-apps:
+  variables: *STATIC_APPS
+  <<: *VS2013_x64
 
 VS2013-64-bit-static-no-apps:
-  variables:
-    BUILD_PLATFORM: "VS2013"
-    ARCHITECTURE:   "x64"
-    SHARED:         "FALSE"
-    APPS:           "OFF"
-  script: "CI\\Windows.bat"
-  tags:
-    - VS2013
-  artifacts:
-    paths:
-      - build-release/*.exe
+  variables: *STATIC_NO_APPS
+  <<: *VS2013_x64
+
+VS2013-32-bit-shared-apps:
+  variables: *SHARED_APPS
+  <<: *VS2013_x32
+
+VS2013-32-bit-shared-no-apps:
+  variables: *SHARED_NO_APPS
+  <<: *VS2013_x32
 
 VS2013-32-bit-static-apps:
-  variables:
-    BUILD_PLATFORM: "VS2013"
-    ARCHITECTURE:   "x32"
-    SHARED:         "FALSE"
-    APPS:           "ON"
-  script: "CI\\Windows.bat"
-  tags:
-    - VS2013
-  artifacts:
-    paths:
-      - build-release/*.exe
+  variables: *STATIC_APPS
+  <<: *VS2013_x32
 
 VS2013-32-bit-static-no-apps:
-  variables:
-    BUILD_PLATFORM: "VS2013"
-    ARCHITECTURE:   "x32"
-    SHARED:         "FALSE"
-    APPS:           "OFF"
-  script: "CI\\Windows.bat"
-  tags:
-    - VS2013
-  artifacts:
-    paths:
-      - build-release/*.exe      
+  variables: *STATIC_NO_APPS
+  <<: *VS2013_x32
       
 Doc-publish:
   only: