no buffer clean if mouse.get_last_event
NF: mouse quitting events
NF+DOC: keyboard, method to get and set pause and quit_keys
BF: using pause and key key correctly
Merge branch 'developing' into exit_android

Conflicts:
	CHANGES.md
Merge branch 'developing' into exit_android
Merge branch 'developing' into exit_android
backport: merge branch 'developing' into exit_android

Conflicts:
	CHANGES.md
Merge branch 'developing' into exit_android

Conflicts:
	CHANGES.md
minor
update
process_mouse_quit only for mouse when polling
minor
only get_button_down processes pygame queue
Mouse.process_quit_event must be static
Mouse.process_quit_event upate
bug fix
Merge pull request #33 from expyriment/exit_android

Exit android