#
Committing before I break this again - reverted to using
DataOutputStreams for now, ObjectOutputStream is more complex and was
throwing corrupted stream exceptions - may have to .flush() in the right
places. 
Mouse click on client GUI sends int to server, server sends int back to
all clients who update the appropriate Land with a colour - all GUI
updates must be done on JavaFX thread - Platform.runLater() does this
'at some unspecified time in the future', could be problematic but seems
to do it instantly for two clients.