Staggered LED configuration; more
Staggered LED configuration; more

Staggered config looks a lot better up-close.
Compute (logical?) width/height on the fly.
setAt(), fillRow(), fillCol() to do the right thing with these.
setAt() not yet implemented for staggered.
mapRange() takes the guesswork out of mapping the 0-100 sliders to the
values we want; helps us rethink the size/distance/intensity
calculations to be more correct (I think).
Various other tweaks.

hobzcalvin/blume,hobzcalvin/blume,hobzcalvin/blume,hobzcalvin/blume