Wait_for() to have a polling version and an interrupt version.
	Polling version to have a downsample count as argument.
(done)(documented) Pclock
Run_after(&Player);  &Player || ANY, ONCE | CONTINUOUS
Run_before(&Player); &Player || ANY, ONCE | CONTINUOUS
Rm_clist()
(done) Kill cyclic list directive.
(fixed) P0 used all by itself is not initialized.
(done)(documented) Alias()
Pitch, Rhythm, Key, Octave, may blow up on Stop Kill and Hold.
Unwait_until()
