Functions for modeling Performers (based on Steven Yi's Python Orchestral 
Composition Library).  Uses 8 pfield format:

p1 - instrument 
p2 - start time
p3 - duration
p4 - pch1 
p5 - pch2
p6 - amplitude
p7 - space (Left: -1.0, Right: 1.0)
p8 - articulation

Score note should leave out p1, to be filled in by Performer.  


(create-performer instr amp-adj space & {:keys [name tuning], :or {name "Performer", tuning nil}})


(perform performer notes)
Default performance method for Csound-based scores (8 pfields)