Organised imports
Serialize entity instead of writing to ByteBuffer

The UDP packets sent to the ViewReceiver from the ViewSender consisted
of an entity object that was serialized by manually writing data to a
ByteBuffer (mainly because I didn't know of java.io.Serializable).

When an entity write to the ByteBuffer it cleared the drawEventQueue as
a side effect (by popping the elements onto the ByteBuffer). Since the
program does not write to a ByteBuffer Entity.clearDrawEvents() is
called after every packet is sent.

Several methods were updated to take an Entity as an argument instead of
a ByteBuffer.