Remove malformed comment
Add Ship Placement Screen

When starting the game, the player must now place their ships on the
grid. The ships can be rotated. Already placed ships can't be removed.
When all ships are placed, a button to advance to the game proper is
enabled.

The code in GUI.run() looks like ass, but it works. I'll try to clean it
up and add some documentation later.
Remove redundant method.
Clean up the code and add Javadoc
Change indentation to tabs
Change indentation to tabs
Clean up GUI code

GUI class now has a nicer structure. Still needs Javadoc though.

Add a hashmap for color lookup instead of the old color constants.