GStreamer Buzztard classes

GstBtAudioSynth — base audio synthesizer
gstbtenvelope — envelope base class
gstbtenvelopeadsr — attack-decay-sustain-release envelope generator
gstbtenveloped — decay envelope generator
gstbtfiltersvf — state variable filter
GstBtMusicEnums — various enum types
gstbtoscsynth — synthetic waveform oscillator
gstbtoscwave — wavetable oscillator
GstBtToneConversion — helper class for tone unit conversion