Survival improvements and fixes

game 168078, version #60387 (win)

When grenades exploded outside screen boundaries, game crashed. This now fixed. This update also includes new GFX and other changes, such as:

• New enemy type: medic
• Improvements on AI, specially for carrier (the enemy that takes players as hostages)
• Performance improvements on survival
• Players can't throw weapons anymore in single/coop mode
• New UI is in progress. You'll notice new ammo counters and a new font.
• Disabled Chromatic aberration for now. ATI users experienced issues.

Demo version is also, now live.