This update is a major cleanup of a wide variety of subtle issues with the game.  Thanks to those who played this and found errors I had not seen.  Keep it up!  I'm sure there are more that I missed.

Features Added:

• Ship now recoils when firing weapon.
• Extra Life can be earned every 10,000 points.

Bugs Fixed:

• Background music now transitions correctly.
• Small ship spawn rate when only one rock remains is fixed.
• Velocity of the Player's ship is capped to prevent overflow errors.
• Player's score correctly resets to zero when the ESC button is pressed to return to the Main Menu.