Openable treasure chests (i.e. Generic dynamic spawning)

made a dynamic spawn class. It operates very similar to a typical static spawn node with a few key differences:

* the type of the node is "spawn"
* the type of the node it generates is in the tmx property list as  "nodeType"
* the way to generate the node is called spawnType

We support 'keypress' and 'proximity' for spawnType. If "keypress" is used the dynamic spawn node manifests itself as a treasure chest. When the user touches the chest and presses the interact key, the chest will open up and generate the desired node.

If "proximity" is used the dynamic spawn node has no visual manifestation and every so often will generate a new node as long as it hasn't reached its threshold(spawnMax)

all of the other parameters that the node would normally have should also be in the properties list.

I have deletable examples of how to do this with a weapon in gay-island-2 and with materials and enemies in black-caverns.