made Voices concrete and introduced synth ABC

moved more calculations to SineVoiceInfo in preparation of making him the synths

Revert "stopped passing in the gate info to the SineVoiceInfo fillBuffer"

This reverts commit 54741fa66705176fd7fee99efaac33176bd95cda.

made scale a private instance variable

pulled off some shared env logic to envelope.cpp

removed SineVoice and made a generic Voice that should work for everything

introduced synth ABC

moved sinevoiceinfo out of voices

added gentags script

renamed SineVoiceInfo to SineSynth

moved SineVoiceInfo files to SineSynth

moved sinesynth to Synths directory