font problems

[Werner LEMBERG]

To make good doc builds of LilyPond it would be important IMHO to have
all necessary fonts included in the docker images.

Here's a list of 'foreign' fonts (or font families) that are not
correctly set up currently.  In particular, I think we should avoid
non-free fonts for demonstration purposes, replacing them with other
fonts where necessary.


* Documentation/snippets/changing-the-default-text-font-family.ly:

    Times New Roman
    Luxi Mono

* Documentation/snippets/changing-stanza-fonts:

    DejaVu Sans

* Documentation/snippets/utf-8.ly:

    [The Japanese text example doesn't have a special font setup; it
     tries to use the global setting, which is

       Linux Libertine O,serif   .

     However, 'Libertine' doesn't cover Japanese, thus a
     platform-dependent fallback gets used (on my box, for example, it
     is 'Droid Sans Japanese').]

    Linux Libertine O
    Linux Libertine Mono O


* input/regression/font-name.ly:

    Times New Roman
    Luxi Mono
    Bitstream Vera Sans

* input/regression/metronome-mark-formatter.ly:

    Times New Roman

* input/regression/markup-compound-meter.ly:

    The character 'e' in on of the `\compound-meter` functions doesn't
    exist in 'Emmentaler', thus a platform-dependent fallback gets
    used (on my box, for example, it is 'Roboto-Regular').

* input/regression/musicxml/31a-Directions.xml:

    The characters 'abc' are used in the argument of
    `make-dynamic-script`; they don't exist in Emmentaler, thus a
    platform-dependent fallback gets used.


* Documentation/en/notation/text.itely

    Times New Roman (3×)
    Luxi Mono
    Bitstream Charter
    Bitstream Vera Sans