Run static type checking with Eclipse

After editing the files in Emacs, the hands-down best editor in all of
history (especially with multiple cursors), I've been able to test what
I wrote and make sure all the Ts have been crossed, etc.

A few minor things, like not enumerating the player sprite-sheet assets
in `BSAssets` and a swapped argument listing here and there.  A couple
(mass) mistypings and all done.