:pencil2: generalize `write`; and, M-x delete-trailing-whitespace
tighter event handler with slide! and undo!
:mag: resizable arena

I think there's actually something wrong with my clean-n-arena macro;
I wanted a `seed` function that would return the initial arena already
seeded with tiles, but the compiler was complaining about not being
able to use a symbol as an integer, I think as if the current form of
clean-n-arena can only take integer literals and not parameters (!?).
look before you Uncaught Error: Index out of bounds
starter three-interface
:sparkling_heart: three-interface is default, resizeable too
:revolving_hearts: merge branch 'three-interface'
GitHub :ribbon: link, seeding constant consistency