cleanup, making bills work properly

mostly cleanup
bulletbill game works properly

cleaned up
added interface for everything that will be bounded in a screen
renamed lobby > ballgame because it made no sense
fixed errant “out of screen” bill functions
bills fire from the same place and at the same time and speed every
time — will change
it’s still kind of easy to evade bills. probably has to do with how
often the world is updating… probably set ticks to be 0.05 > 0.01s and
slow things down (visually) by a fact of 5 to fix this
should also remember to have bills  “overshoot” and fall off the
top/bottom of the screen, not just the left