StringMap is not StringToUniqueIntegerMap without syncing

engineItemMap is back in SpoutEngine to correctly sync materials
Datatable syncing fix is next
Entities' datatables now get sent

Update for API changes:
Session doesn't get a datamap
DatatableComponent now gets an isDirtyMethod
Implement ClickRequest and ClickResponse.

ClickRequest is C->S and is for asking the server if this click is
allowed.

ClickResponse is S->C and is for instructing the client if the click is
allowed or denied.

This is the first steps to a framework for controlling GUIs from the
server.

Signed-off-by: Chris Sanders <zidane@outlook.com>
Send input to server, server sends EntityTransformMessage

This will change soon
Implement the unload function of ChunkDataMessage
fix(?) ChunkMeshBatchAggregator position methods (I don't know if these were broken, but they're fixed now)
These need to be called in doRelease so that super.finalize() happens