Allow player to switch between controlling different ants

[cjhoward]

The player should be able to control any ant in the colony. There are currently two ideas for how to transfer to controlling a different ant:

1. The player moves the controlled ant within range of another and initiates trophallaxis, during which the camera orbits around, then control is transferred.
2. The player zooms out to antkeeper view and selects an ant with the mouse or control stick.