Swapped population and SI to L4D1 models

additions/changes:

• Shattering glass
  
• Unchanging weapon spawnpoints
  
• Outside surrounding area from Dead Air greenhouse map
  
• Surrounding rooms have textures, to play VS Survival
  
• Different Elevator crash sound
  
• removed all unused content

Made weapon spawns not random.
Made elevator button glow.
Made elevator door break faster. in case you're stupid enough to get stuck.

Fixed non solid office walls. Smokers will no longer get you through the wall.
Fixed navmesh in places where infected got stuck.
Made throwable object spawnpoints the same on every map launch
Added two Defibs.
Added five melle weapon spawns (possible melee's fireaxe, katana, machete, crowbar, cricket_bat and baseball_bat)

Fixed workshop thumbnail. This requires an addon update. thanks valve.

attempt at fixing thumbnail.

fixed addon thumbnail not showing up. thanks steam.