Changes from MusiXTeX 121 to 122:

  +  bi and sc font definitions added; sl and tt definitions for musixsty moved 
  +  explicit font choices for \txtfont replaced by generic commands
     \smalltype\it etc.
  +  \pdlud \halfwidthbigwedge and \raise height font-dependent
  +  \zbreath and \cbreath use BIGtype rather than BIGfont