Alpha 0.6.2

CHANGES TO CONQUEST.JAVA
Made all JButtons and JLabels final.
Set GUI tyle from Nimbus to Windows.
Added checkPossibleMoveDirections() method. Blanks out move buttons
depending on the selected unit's location, so that the unit cannot go
out of the screen.
selectUnit() and prepareMove() methods now calls the
checkPossibleMoveDirections() method.

CHANGES TO CONQUESTMAP.JAVA
Reorganised code.
Fixed issue in setGridOccupied method where units took the wrong
coordinate values of other units.
Fixed issue where a unit would move across by two grid tiles for no
apparent reason.