Issue 343: Migrate from literal string event names to 'constant' variable event names
Project Member Reported by dennd...@gmail.com, Oct 12, 2010
i.e., instead of:
    animobj.connect('on_animation_complete', myhandler)

we do this:
    from pymt.events import ON_ANIMATION_COMPLETE
    animobj.connect(ON_ANIMATION_COMPLETE, myhandler)

And for backwards compatibility, in pymt/events.py:
    ON_ANIMATION_COMPLETE = 'on_animation_complete'

Why all this? The interpreter will let us know immediately if we misspelled the event name, e.g. ON_ANIMATOIN_COMPLETE would immediately raise an error, but 'on_animatoin_complete' would only ever surface at runtime.