Menu and Audio Update

-Added an audio manager to control sounds in the game

-Removed "PRESS ANY KEY TO START" cause it was silly

-Added three clickable options to the title screen, 'Play', 'Options', and 'Exit'

-Added a UI handler

-Menu can be controlled with keyboard

-Added the ability to pause

-Added a pause menu

-Added a volume slider to adjust the sound in the game

-Engine sound is generally quieter

-Entire game is quieter by default

-Added the ability to go back to main menu (this ends your current game and does not save the score)

-Fixed a bug where you couldn't move on to the next level due to killing more than one enemy on the same frame