Added partial OPCODE framework, moved signals.

Added handling for different OPCODE properties on received object so we
can differentiate between attacks/movement/death/etc.  Will be slightly
more refined later.  Fixed a couple errors in SoundManager and added
Stack which I forgot last time.  I also moved Signals to the correct
location (under "org").  Implemented SoundButton on the SubmitButton to
show how it works and MusicManger.