StartTowerAttributes

Start with the extendable TowerClass and a type of tower to extend it.
Merge remote-tracking branch 'origin/master'

Conflicts:
	Library/CurrentLayout.dwlt
	Library/InspectorExpandedItems.asset
	Library/ScriptAssemblies/Assembly-CSharp.dll
	Library/ScriptAssemblies/Assembly-CSharp.dll.mdb
	Library/assetDatabase3
	Tower_Defence.userprefs