make Event serializable and implement Connection.send event()
removed unused import
Merge branch 'master' of https://github.com/asavonic/DotsBoxes

Conflicts:
	src/dotsboxes/events/Event.java
	src/dotsboxes/rmi/Connection.java
	src/dotsboxes/rmi/ConnectionManager.java
	src/dotsboxes/rmi/NodeRegisterImpl.java
Implemented RMI double-linked connection