2 - y-refpoint for rests should be the 4th staffline (gclef: b')
15 - move to OpusTeX fonts ? (no!)
16 - include important spacing dims in TFM?
17 - lilyrules.mf for different rules (lines) ?
18 - check out Adobe Sonata/Petrucci font layout. They are the
19 standard for Music fonts
20 - hack up GS to do round pixels iso. square pixels.