Qualtran

Qualtran is a set of abstractions for representing quantum programs and a library of quantum algorithms expressed in that language to support quantum algorithms research.

Closed bounties:

• $200 | Correct lint issues exposed with update to pylint-3
  closed by: micpap25
• $100 | Add docstrings to basic gates like CZPowGate, Rx, Ry
  closed by: ahkatlio
• $200 | Add a pretty formatter for rotation angles so we can have nicer musical score diagrams
  closed by: jbolns