Part source and colla parte definitions

[noteflakes]

Parts should be able to source from other parts. For example, an oboe part that plays with the soprano in a choral, or a cello part that plays the continuo part, but without the figures.

Two ways to define part sources. The first:

- parts:
  - oboe1:
    - source: soprano
    - lyrics: hide
  - flute1:
    - source: violino1
  - violoncello:
    - source: continuo
    - figures: hide

The other way is define colla parte settings, which invert the setting:

- colla_parte:
  - soprano: oboe1, oboe2 // oboe1 & oboe2 double the soprano part
  - continuo: violoncello // the violoncello doubles the continuo part