V0.2 - added crystal and freezing

Added the ability to shoot a crystal and freeze the enemy in time.

By default, the crystal lasts 5 seconds and freezes enemies for 10.

While the enemy is frozen, you can use it as a platform, being able to collide with it like a wall, and land on and jump off of it like a floor.

Since the enemy is immune to spikes, you can use it to get past large gaps you normally wouldn't be able to.

The gist of the game is here finally!