pull up common functionality of inference method classes
Change order of include dirs in unit tests cmake
fix doxygen warning
Merge pull request #1427 from iglesias/develop

Change order of include dirs in unit tests cmake
Merge pull request #1428 from votjakovr/feature/gp_refactoring

Pull up common functionality of inference method classes
Merge pull request #1429 from votjakovr/feature/fix_doxygen_warning

Fix doxygen warning