fix for a terminally minor graphical artifact
Revert "fix for a terminally minor graphical artifact"

This reverts commit c31f8008555988bb34ea7b1d9aaa1802988c8e9b.
gonna use this to test for collisions with arrows, possibly spots too
First shot at collision detection for arrows. Doesn't work.
ok I think arrows collide alright
collider for spots, too
Rearranging the touch handling logic to make it easier, later on, to detect multiple hits and disambiguate
decrufting (and one docstring)