Allow articulations to perform transformations on incoming notes

[jtackaberry]

To provide more parity with Cubase expression maps output mapping, articulations should be able to:

1. Transpose
2. Adjust velocity via a multiplier (for e.g. accents)
3. Interpolate velocity within a defined min and max value
4. Interpolate pitch within a defined lower and upper note pitch

Interpolation works like outval = inval * (max-min)/127 + min and would be evaluated after the fixed adjustments.

Cubase also allows outputting a specific note length. The use-case for this is much less interesting IMO as fixing note lengths precludes massaging performances. Also, it's much harder to implement since it would require timing the note-off, potentially queuing it for a later execution of @block and then ignoring the actual note-off.

Design

Reabank

Propose these articulation level attributes:

1. velrange=<min>-<max>
2. pitchrange=<min>-<max>
3. transpose=<numpitches> (can be negative)
4. velocity=<coefficient> (A number between 0-10 allowing two decimals of precision)

The attribute names are a lot more verbose than the existing ones since a) these are pretty rare and b) the reabank GUI will eventually render the complexity/readability concerns of reabanks moot.

RFX

Use the new extensions capability to reserve an articulation extension for this feature. Stored in the extension:

1. Transposition: 7 bits
2. Velocity multiplier: 10 bits
3. Min/max velocity: 7+7=14 bits
4. Min/max pitch: 7+7=14 bits

This would be two 24-bit slots (if packed as (14+7) + (14+10)).

Velocity multiplier is divided by 100.0. 10 bits allows for a range of 0-10 with 2 decimals of resolution.