Play/Edit mode

[lane-s]

Currently there is a concept of play/edit mode.

Play mode causes the wands (mallets, batons, whatever) to appear in the player's hands so that they can play notes. It also disables the UI pointer so that the user doesn't accidentally click UI elements while playing.

It is worth considering eliminating the need for two different modes by:

1. Having an object which dispenses wands. This will require some more design thinking since the user doesn't need to constantly hold the grip in order to hold the wands.
2. Disabling the UI pointer when the wands are held and possibly giving the player manual control over whether the pointer is active.

Note: there is currently a bug related to switching modes:
Switching modes while a wand is inside of a NoteOrb does not call the TriggerExit on the NoteOrb, so the NoteOrb erroneously continues to listen for trigger presses.