The default is that hiniting is enabled, which causes some text
metrics (notably width) to be rounded to integer values, which makes
spacing more consistent. This default is backward-compatible. The
non-default 'unaligned mode refrains from rounding, which makes metric
information scale correctly and improves output for PS/PDF (such as
Redex output).
The `text' function from `slideshow/pict' defaults to
disabling hinting --- which is consistent with its default to combine
text instead of drawing character-by-character -- so slides and Redex
inherit the improvement.
