Use relative include path, fixes #15

9 jobs for include-fix in 6 minutes and 39 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #79731
VS2015
VS2015-32-bit

00:01:17

passed #79730
VS2015
VS2015-64-bit

00:01:32

passed #79729
VS2017
VS2017-32-bit

00:01:22

passed #79728
VS2015
VS2017-64-bit

00:01:42

passed #79725
Linux
clang-c++11

00:04:09

passed #79727
Linux
cppcheck

00:06:38

passed #79732
Linux
doc

00:00:12

passed #79724
Linux
gcc-c++11

00:04:08

passed #79726
Apple
macos-c++11

00:03:09