Blender Git Loki

BGE: python API initialization cleanup

The goal of these changes is to Close T40132 and to get rid of the 'PyRun_SimpleString'

Hilighted changes are:
- consistent naming and initialization of BGE submodules
- initialization of the 'bge' module as a proper module
- using PyDoc_STRVAR instead of static char*
- generic cleanup (unused arguments, logica ordering, naming and whitespace)

Reviewers: campbellbarton

Maniphest Tasks: T40132

Differential Revision: https://developer.blender.org/D983