Refactor dynamics

[trevorbaca]

• Consider replacing niente dynamic with LilyPond \! hairpin-stop.

• Add interpolated dynamic handler

For terraced (discrete / nonhairpin) but interpolated dynamics: p, mp, mf, f ... etc.

Method will count underlying number of leaves / plts / attachment targets; then interpolate between two values; optional LMR-style specifier to direct growth at edges (or middle).

• Add fractional dynamics

p+1/2, p-1/2

p+1/3, p+2/3, p-1/3, p-1/3.

And so on.

• Add semantic check for incorrectly parenthesized dynamics. So p ... (pp) < f will be found.

• add hairpin staff padding check; raise "you probably mean baca.dls_staff_padding() instead."

        baca.hairpin(
            'p < f',
            abjad.tweak(7).staff_padding,
            )

• integrate indexed tweaks

        baca.hairpin(
            'ff >',
            (abjad.tweak(True).to_barline, -1),
            )

• add force_final_dynamic keyword

        baca.hairpin(
            'ff < fff >',
            force_final_dynamic='ff',
            pieces=baca.plts(),
            )

• Raise exception when mf -- ! enchains niente o< f. Causes two LilyPond \! commands to attach to same leaf.

• Add sequential dynamics. Something like baca.hairpin('p < [mf, f, ff]') to give p < mf, p < f, p < ff on successive applications.

• Add interpolative dynamics. Something like baca.hairpin('p < [mf,, ff]') to interpolate from mf to ff according to total number of applications; allow keywords or other specifiers to control for fraction dynamics and repeat values.

• Add baca.dynamic('f', allow_repeats=True) keyword to generate sequential f not colored as redundant.