cmn has its own font now

[To: cmdist]

The new cmn (ccrma-ftp.stanford.edu:/pub/Lisp/cmn.tar.gz)
no longer uses either the Sonata or Petrucci fonts, but
instead has its own built-in.  This change was inspired
by Matti Koskinen who translated the MusicTex font to
Postscript.  I took the opportunity to rewrite the lower
levels of cmn completely, so this version is not entirely
backwards compatible with the previous version -- see
the list of changes in cmn-init.lisp for details.  I
also added an X/Motif previewer.