saugns v0.3.5b. Fixes for 'S a' and "@label" syntax.

 * 'S a' (Set amplitude multiplier):
   Apply multiplier to amplitude ramp target,
   not only the normal or initial value.
   (This was missed a long time ago.)
   Rebased down to v0.2.3.
 * Change which flags are checked to
   allow/disallow 'r' (rel. freq.) and 'i' (inf. time),
   fixing syntax for "@label" references.
   Rebased down to v0.3.1d.

Also change op list code to include pointers instead
of direct instances for modulator lists in parse data.
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