+ keys are 'collected' on impact with Nut

+ tile_key
+ graphic
+ keys bop up and down
~ fixed bounce and oscillate
===
+ keys are "collected" on impact with Nut

! tile_lock
+ graphic
! removes the tile it is on top of.

! tile_key > tile_lock
each key has it's own lock
on collection, the key opens the lock

! pretty effects
! tile_key
! passive: shines nicely
! collected: explodes in shines

! tile_lock
! passive: shines a bit
! unlocked: drops lock, bounces