Update v0.9.8f15: new mission, new tanks and more

This is a small patch to fix various major problems, and add some new content.
Here's some of the changes:

New features
• Added 4th Kos mission.
  
• Added M3 Stuart (USA and UK).
  
• Added 2 bunkers.
  
  Fixes
• Fixed road decals.
  
• Fixes in AI.
  
• Fixes in fog and lighting.
  
• Various other fixes.
  

Thank you,
Marco