Merge pull request #87 from eile/master

Fix doxygit target on missing organization
Merge branch 'master' of https://github.com/Eyescale/CMake
Common adaptations for more complex projects than Hello:
* Add api.h generation to CommonCode
* install_files and common_library handle absolute paths
* common_library handles subdirectories for header install
* Sort files in common_library for convenience
* Documentation update
* dll_export version class