This patch adds the submodule app to bge. apps contains constants similar to bpy.app, particularly version (tuple of three ints like 2.75.1).
It was requested in T43918 and set as TODO.
The patch also adds rst doc for the module.
Reviewers: moguri, kupoman, lordloki, panzergame, campbellbarton
Reviewed By: lordloki, panzergame, campbellbarton
Subscribers: marcino15
Projects: #game_logic, #game_python, #game_engine
Differential Revision: https://developer.blender.org/D1348
