Added explicit widths to the 6502 vectors.
Two changes to Apple II hi-res visualization:
(1) Allow the row stride to be any value >= 1. This is useful
when data is stored in column-major order, i.e. it's a two-byte-wide
shape, with all of the data for the first column stored before the
data for the second column. (Set the row stride to 1, and the
column stride to the bitmap height.)
(2) Modify the layout of grids (sprite sheets and fonts), so that
we're closer to square when the item counts is low. Otherwise the
thumbnail just looks like a dashed line. (This one is strictly
cosmetic.)
a2e7c88fc9