Birds and phases

After much hackery, there are now swooping birds that appear mid-game. They're not quite complete yet -- they don't have words above them -- but they do float, hover, and dive bomb you, like crows or magpies sometimes do. Eventually they'll have corresponding words to type, and their attack will hurt/stun the player for a second.

There are now also phases. Right now there are three phases, each with progressively harder words, and closer together. Each phase lasts 15 seconds.

Next I need to fill out the night situation a bit. Let you turn your flashlight on (it's been off for the last few builds), and add a phase 4 night bit, perhaps with pumpkins, skeletons, and who knows, maybe even a boss.

Also, need to implement the chasing wolves/death mechanic.