Use stylistic sets to access chip-specific characters.

Use stylistic sets to access chip-specific characters.

Now, for characters where the various SAA5050 variants differ from one
another (or from my aesthetic sense), a "stylistic set" lookup can be
used to force the use of the variants from a particular chip.  "ss01"
gives SAA5051 shapes, "ss02" gives SAA5052 shapes, and "ss04" gives
SAA5054 shapes.  Bedstead's usual shapes are entirely compatible with
the other chips in the series.