Replace ternary grace=None, pitched=None flags with boolean flags

[trevorbaca]

The grace=None, nontrivial=None, pitched=None flags are the only ternary flags in the system.

• Replace grace=None with exclude_grace=False, exclude_nongrace=False.
• Replace nontrivial=None with exclude_nontrivial=False, exclude_trivial=False.
• Replace pitched=None with exclude_pitched=False, exclude_nonpitched=False.

The refactor sites are abjad.iterate.*(), abjad.select.*().