Change Aeolus default to Equal Temperament

The default Aeolus temperament was Mean Tone which sounds out of tune to
our modern ears. I have changed the default to 5 (Equal Temperament) and
added information on how to change this at the head of the file.
On a new installation, "Preferences" crashes

On a new (Linux?) installation, if no sound output is enabled, opening "Preferences" crashes.

In mscore/preferences.cpp, mscore/musescore.cpp, mscore/scoreview.cpp seq is accessed but set to 0.

Added some safeguard checks.

(Same for master as another recent patch for qt5)
transpose & render unrecognized chords
token-based rendering & other improvements
simplify and improve parsing and rendering of parens and commas
add hidden style option to suppress loading of chords.xml
add facility to define rendering by token in chord description file
add class attribute handling to token declarations
save token definitions as part of chord list
revert Jazz Lead Sheet to go back cchords_muse for now
fix handling of 0 for half-diminished
fix for scores that change from old-style chord description to wysiwyg
fixes, and change NULL to nullptr for now
nullptr => 0
Adds a score style for selecting the position of naturals in key signatures:

- NONE (except when changing to CMaj/Amin)
- BEFORE accidentals
- AFTER accidentals (but always before if sharps <=> flats)

Default is NONE.

When reading old scores (<= 1.14), a BEFORE setting (as in 1.3) is provided.
Fix tests.

As test scores are in 1.14 format, they get an extra keySigNaturals = BEFORE style.

Updated reference scores.
fix biab import and test

Scores created via bb import were saving empty <name> tags, which was
not ideal.  They now create valid <name> tags.  Test was not expecting
any <name> tags at all, so it has been updated.
fix parts test

Scores now record <name> tags for <Harmony> objects, so references in
tests updated to reflect this
Merge remote-tracking branch 'origin/master' into AeolusUpdate
Fix #21110 - position the text of glissando according to its physical sizes and no longer by a hard-coded vert. offset

It should also fix #20970: collision of glissando with ledger lines.