Merge branch 'face_normals' into 'master'

only compute normals for faces that are not deleted

See merge request !141
24 jobs from master in 88 minutes 21 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #33341
Linux
Doc-publish

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VS2013
VS2013-32-bit-shared-apps

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VS2013
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VS2013
VS2013-32-bit-static-apps

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VS2013
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VS2013
VS2013-64-bit-shared-apps

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VS2013
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VS2013-64-bit-static-apps

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VS2013
VS2013-64-bit-static-no-apps

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VS2015
VS2015-32-bit-shared-apps

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VS2015
VS2015-32-bit-shared-no-apps

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VS2015
VS2015-32-bit-static-apps

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VS2015
VS2015-32-bit-static-no-apps

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VS2015
VS2015-64-bit-shared-apps

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VS2015
VS2015-64-bit-shared-no-apps

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VS2015
VS2015-64-bit-static-apps

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VS2015-64-bit-static-no-apps

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Linux
clang-c++11

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clang-c++14

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cppcheck

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gcc-c++11

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gcc-c++14

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Apple
macos-c++11

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Apple
macos-c++98

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