BGE: Fix T43918: adding submodule bge.app including attribute version.

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

doc/python_api/sphinx_doc_gen.py

@@ -234,6 +234,7 @@ else:
     EXCLUDE_MODULES = [
         "aud",
         "bge",
+        "bge.app"
         "bge.constraints",
         "bge.events",
         "bge.logic",
@@ -1669,6 +1670,7 @@ def write_rst_contents(basepath):
         fw("   bge.texture.rst\n\n")
         fw("   bge.events.rst\n\n")
         fw("   bge.constraints.rst\n\n")
+        fw("   bge.app.rst\n\n")
 
     # rna generated change log
     fw(title_string("API Info", "=", double=True))
@@ -1825,6 +1827,7 @@ def copy_handwritten_rsts(basepath):
         "bge.texture",
         "bge.events",
         "bge.constraints",
+        "bge.app",
         "bgl",  # "Blender OpenGl wrapper"
         "gpu",  # "GPU Shader Module"