Progress on touch input.

- Add a 'fire' button on the right.
- Refactor input CSS.
- Add rbound method for bounds checking.
Don't call input.init() in heartbeat().
Better bounds-checking on players.
Forgot to remove a line.
Debug fire button.
Use isFiring().
Small refactor.
Lasers stop at screen edge.
Make the player sticky in the screen.

This is the common R-Type behavior.
Examples of enemy types.

Extends the Enemy class with two new types, Boss and Mook, demonstrating
how Enemys will be constructed.

Boss exhibits internal movement rules that demonstrate overriding
Enemy.update().

Finally, tweaked params on Mook position to make testing more
interesting.
Add a score.
Move unit definitions out of level.js.
Remove enemies when they leave the screen.
Make safe the score increment.
Some enemies shoot back.
Example of moving enemies.
Refactor Player collisions.
Merge pull request #2 from jsocol/master

Progress!