Merge pull request #3 from Lakon/development

Development merge
Fixed crosshair to properly follow mouse movement.

Crosshair now follows the mouse regardless of where the player is in
world space.
Gun now properly aims at crosshair.

Gun correctly aiming
Bullets now killing enemies.

Bullets now properly destroyed when they leave the game screen. Enemies
can now be killed with bullets. Still need to destroy bullets on
collision with enemy,
Bullets now destroyed properly.

Bullets are now being destroyed on collision with enemies that are
alive. They pass through dead enemies.
Adding first enemy health implementation.

Basic enemy health and OnHit function added to enemy class.
Add sound when enemy is hit.

Play the enemy killed sound when hit. Eventually we want to use a
different sound, but I'm in haul ass development mode.
Different enemy classes added. Enemy factory added.

Using a factory pattern to construct different enemy types by passing in
the enemyType string. Right now, enemies only have different animations
and types.
Now displaying health

Display the player's health on the screen.
Just added tilesets to the new level
Merge pull request #3 from MikePaNtZ/development

Development