Blender Git Loki

Esc as input for Key Buttons (e.g Logic Brick Keyboard Sensor)

After talking with Brecht he agreed on allowing Esc to be used as input for key input butons.
In order to let the user to cancel an input it can cancel it clicking outside the button.

Also replacing manual check by ui_mouse_inside_button in ui_text function
(patch reviewed (and helped) by Matt (but the change on ISHOTKEY, that's on my own risk ;))