Percussion charts should be autogenerated

[David Kastrup]

The current percussion chart has been generated manually by

commit 6beb9fee2733de250ecedd0573b4d0b577cb51a3
Author: James Lowe <pkx166h@gmail.com>
Date:   Sun Aug 10 09:34:20 2014 +0100

    Doc: Appendix - Articulations and Ornamentation - part 3
    
    Issue 1189
    
    Create Texifo @multitable entries for the
    List of Articulations appendix.
    
    As there are a lot of separate scripts being
    documented this Issue is going to be split
    into multiple, smaller, parts to aid in the
    review process. Part 2 was commit 4d6f2a27cc
    
    This is part 3 and while not strictly
    'Articulations and ornamentations' covers
    the percussion scripts.
    
    I have also set the @code{} script examples into
    the same column as the @lilypond examples; saving
    a significant amount of wasted page space. I have
    removed unnecessary lilypond-book variables making
    the texinfo code less noisy.

It replaced the inclusion of
Documentation/en/included/percussion-chart.ly that currently is still
done by the outdated German documentation.  However, percussion-chart.ly
is not really "autogenerated" either but just uses LilyPond rather than
Texinfo source code for supporting a hardwired set of percussion notes,
so it's not like this commit was a regression in some relevant respect
but merely a change of implementation.

The problem with the current table is that it covers (presumably) all
drum types known to the input but then uses the standard percussion
table for typesetting it.  Including those drum types that aren't in the
standard percussion table and are all printed the same, which is almost
the last two pages of the table.

And not all of the given notes have a MIDI rendition, either.  Part of
the reason is that the MIDI mapping has no notion of the current drum
kit (the MIDI instrument for MIDI channel 10) where different drum kits
have somewhat different instrument assignments in GM2.  Of course, that
is not a documentation but a functionality deficiency.

And then there are some fairly common instruments like "tam tam" (an
unpitched gong) that are not even in the MIDI GM2 standard and where any
assignment is predicated on the user redefining some patches and/or
using non-standard MIDI registrations.

To get a better headstart for knowing what one needs to tamper with, it
would be nice to give the MIDI instrument number as well where one is
assigned.

-- 
David Kastrup