Cleaning mess in develop branch

Created proper directory tree:
/src
	/ai
	/gui
	/logic
	/test

Cleaned up CMakeLists.txt files, removing commented lines and unused commands,
organizing commands, added better way of finding source files and linking
libraries to executables.

Removed classes that have been written for testing purpouses only and are no
longer needed:
/src/BoardSample
/src/Dollar
/src/Dollar/Dollar
/src/MainWindowSample

Fixed some dependencies on the old files.