[EDIT][#] Add nodes (not just behaviours) in the BehaviourEditor window which allows files to be loaded

[EDIT][!] Loading a behaviour actually loads it in the editor
[CORE][#] Expose the SerialableObjects for the nodes so can be added as known types for the DataContractSerialiser. (This meant could remove the static constructors that were adding the type to a list).
[CORE][#] Removed generic requirement from kAINode (since don't need to know what the type is outside, just the interface).