The midi state now tracks time through block duration; you need to call advanceTime(numSamples) at each callback.
The midi state now stores all CC and pitch events that happened during the block.
Added group polyphony and note_polyphony support, as well as note_selfmask support.
Multiple CCs can modulate pan, amplitude, width, position rather than one.
The voices do not store CC history for the modulation targets and rely on the midi state to provide the events that happened during the last block.
Removed the EventEnvelopes; they're replaced by generic free functions that take as input an EventVector from the midi state; old tests migrated.
Added support for tune_cc and pitch_cc related opcodes.
In all this process, I also removed most of the per-voice temporary buffers and preallocation to replace everything by a BufferPool that distributes buffers around, and can track the maximum buffer usage in debug mode. The number of concurrent buffers are set at compile-time, so it must be adapted to the current processing needs.
