Fleshed out rhythm-maker rotation segments.
Wrote rhythm-overlay segments.
Added minimum-timespan-duration segment.
Rerendered all segments.
Turned off stemlets in RhythmManager.

LilyPond has some occasional catastrophic rendering problems when a beam
crosses a system boundary and only beams rests on the other side.
Improved rehearsal mark formatting.
Rerendered all segments and updated build collateral.