Added support for event properties

NEW: The event callback in rive.play_state_machine() will now also include all event properties in the callback message.

rive.play_state_machine("#model", "my_statemachine", nil, function(self, message_id, message)
	if message_id == hash("myevent") then
		print(message.mystring)
		print(message.mynumber)
		print(message.myboolean)
	end
end)