Python : Add Bake Callback Handler

Thinking about using Textures as cameras, it could be great to export a sequence of baked images. For doing that, we should be able to use callback functions with "bpy.app.handlers." for baking as it's possible with rendering. Then I could make easily my "Render texture sequence" add-on !

It would look like that :

bpy.app.handlers.bake_cancel / bpy.app.handlers.bake_complete / bpy.app.handlers.bake_init / bpy.app.handlers.bake_post / bpy.app.handlers.bake_pre / bpy.app.handlers.bake_stats / bpy.app.handlers.bake_write.

EDIT: Integrated docs.blender.org/api/current/bpy.app.handlers.html