cleaned up the file - had a bunch of random 'recommended' crap that other tutorials were pinning for.
I didn't see the need for this as of yet, so I commented and/or deleted that fluff for now.

Stars are not blitting correctly to the screen (aka as invaders traverse over the top, the stars are
reblitted to the background).

Also added invader mappings/layouts.  Now, anyone can add additional invaders to the screen just by creating
new layouts and adding them to allInvaderMaps (it randomly selects from there and then draws the corresponding
invaders).

TODO:  Make stars parralax in movement to simulate depth.
TODO:  Add more lateral movements, and slow down their progress
TODO:  Add simulated lasers/fights/collisions (much later in dev)
TODO:  Put in prompt for password
TODO:  Implement "0" as a non-invader space so maps can have non-rect formats