Alpha 2.0

Many new changes warranted for the next full update of the game.  Many sounds were added and a few UI issues have been more or less addressed along with other things.

• Anchor points for UI elements now make them more flexible for different screen dimensions.
• Game resolution changed to 960 x 600
• The pause menu now has a replay button and written game instructions.
• Unique firing sounds added for each weapon.
• Ghosts now hiss when hit by the player's projectiles.
• Projectile enemies now make distinct sound when firing a shot.
• Player makes hurt sounds when hit