Remove `FileSystem` module.

stlplus crashes in windows 8 for some reason. All the more reason to get
rid of it and it is not a very important library.
Remove `CodeCoverage.cmake`.

Code coverage is already activated in debug mode.
Merge pull request #119 from DO-CV/maint-remove-codecoverage-cmake

[MAINT] Remove `CodeCoverage.cmake`.
Merge pull request #118 from DO-CV/maint-remove-filesystem-module

Remove `FileSystem` module.
Merge branch 'develop' into fix-image-processing-module