Stencil bounding box

[David Feuer]

Once a stencil has been wrapped in another stencil, is its bounding
box ever used?  I suspect that while a new stencil is built from one
or more existing stencils, it shouldn't contain those stencils in
their entirety.

Update on thoughts for the PostScript part of a redesigned backend system:

- Stop using postscript coordinate translation altogether.  This will
increase the space needed to represent coordinates, but

- Optionally (user option) we can use PostScript binary encoding, so
coordinates can be IEEE floating point numbers, represented 4-5 bytes
of PostScript, which will expand to around 5 or around six, depending,
to make 7-bit ASCII.

Fonts:
- The note/accidental/whatever font should get an encoding vector, if
it doesn't already have one.
- CID fonts should always be used with CMaps

Once this is done, we can use xyshow instead of glyphshow.  Even
better, as we traverse the page stencil to draw the page, instead of
immediately showing the glyphs we put them in a list to show later. 
We sort the list by font and color, so then we only need to switch to
each font once per page.  Each (font, color) pair will typically get a
single xyshow.  Furthermore, we can extract a list of fonts from the
show list, and even make arrangements for font subsetting!

My computer battery is dying now, so I'll send this.

David