Small Fixes, changes and added stuff for 0.521.

Fixes:

• Fixed the FPS getting worse over time.
  

Changes:

• Lowered Superb Needle Gun's damage across all levels by 35%.
  
• Increased the range of the Hefty Sweety Revolver by 25%.
  
• Lowered Max-Ammo for the Sniper from 130 to 50, while increasing the ammo price by 200%.
  

Added:

• There is now a Wave multiplier, increasing Zed's damage and health by 1% for each wave.
  
• There is now a Zed health difficulty multiplier, increasing the Zeds health by 0%/7,5%/12,5%/20% from Scrub/Normal/Hardcore/Kamikaze difficulty.
  
• There is a blue outline on the last 3 Zeds on the map, making it possible to spot the Zeds through walls.
  

Tip of the day: If you die, you are dead for the rest of your life.