HOORAY BUG FIXES, BALANCING, ALL THAT GREAT STUFF!!

Main Updates
   - Complete revamp of the enemy spawning system - now based upon a weight system
   - Added 3 new enemy types
   - The 'Money Per Second' text now displays a rounded amount for clarity's sake

Bug fixes
   - Fixed a bug where the player wasn't able to shoot continously
   - Fixed a bug where the playlist would cycle songs after unfocusing the game window
   - Fixed a bug where the player's idle animation would only play once

Game balances
   - Lost Soul price | 1 mil -> 2 mil
   - Day interval | 11 -> 5.5
   - Lowered the amount prices rise at for a lot of the upgrades
   - Modified stats for all of the enemies