Fix namespace issue with clang.

Signed-off-by: Thomas Klausner <wiz@NetBSD.org>
Issue 3896: add q to the index of Notation Reference
Issue 3898: parser.yy: move figure_list to chord_body

Figures failed to get recognized as music function arguments and possibly
in some other contexts.  Moving them together with chords in < > style
gets rid of that problem.
Issue 3897: Some spring cleaning mostly concerning cumbersome apply calls

Also replaced some uses of zip with multi-list map.
Issue 3894: accidental rule 'teaching' broke

Revert part of "Issue 2745: more fun with accidental rules."

This reverts the part of commit bbca17061fbc7a25ca4050e6d031b3e9562b658e
that deals with the teaching accidental rule.
Issue 3880: bad number formatting in svg path output

This uses ly:format with "~4f" format string rather than format with
"~S" for formatting point lists.  Note that "~4f" has a different
meaning in ly:format as compared to plain format.  This is consistent
with other number formatting.  Also does this for output of color.

The previous output was problematic when the number was an exact
fraction.
Tuplet brackets should reliably not follow kneed beams, regardless of whether Beam::is_knee has been called yet.

This affects input/regression/tuplet-number-kneed-beam-horizontal-fit,
and the following:
{
  \override TupletBracket.bracket-visibility = ##t
  \times 1/2 { c8 c''' c c''' }
}

Is it safe to call Beam::is_knee in Tuplet_bracket::calc_position_and_height?