Added "go back" functionality for selectUnit -- This has actually been a
large pain since the beginning, and I really should have done this
sooner (took like 2 seconds). Anyway, it was changed so that if the user
hits 'x', then it sets the wm to nil and there's a check before moving
on in the main method that it will only go if the wm is not nil.
Changed the println so that it reflects the cancel opton in selectUnit.
Wah hoo.