Added "hide" verb to mousetraps, placing them on the same layer as hidden mice.

Triggered mousetraps and dead mice will be moved back to the top layer.

Monkeys will no longer move randomly while being pulled.
Two config variables added - disable_player_mice and uneducated_mice. The first, if enabled, prevents players from spawning as mice, and the second, if enabled, prevents mice from understanding human speech (which they now do my default)

universal_understand = 1 now allows player-controlled mobs to understand what everybody is saying without necessarily allowing them to talk back intelligibly. Mice have universal_understand = 1 by default.
Removed two variables accidentally copied over from dev
Merge pull request #4070 from RavingManiac/master

Crouching monkey, hidden mousetrap