Small fixing patch

This is a small patch to fix some bugs and improves some smaller features.

Changes:
• Fixed "select mission cover" button wich was sometimes not working.
  
• Added hint for new player when you are trying to damage tanks with HE projectiles.
  
• Now AI drops Panzerfaust after using it.
  
• Small improvements in animations.
  
• It's now possible to open map from inside a vehicle.
  
• Small fixes in tank getting stuck.
  
• It's now possible to respawn on landed gliders.