Quick Perf Wins

[nick-thompson]

There's a bit of low hanging fruit for (minorly) improving processing performance:

• Split out a phasor and a sphasor so that the phasor itself doesn't constantly check for a reset signal
• Pre-calculate T = 1 / sr in the phasor, root, etc
• Approximate the trig functions; sin -> Pade, tanh -> Taylor, etc
• Fast pow and log functions, etc