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)
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.
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.
Smarter algorithm for avoiding collision with start note ledger line.

Added detection of start note dot(s).
Fix #17227 - When creating a score from a template, transposing instruments had wrong key signatures.

Corrected in mscore/file.cpp, by repeating the same test used in ver. 1.3
Merge pull request #368 from mgavioli/Fix_17227_Transp_instr_from_template

Fix #17227 - Wrong transpositions in scores from templates
fix #21119: Templates with parts create corrupted score
Merge pull request #364 from mgavioli/Style_for_natural_pos_in_key_sig

Score style for natural position in key signatures
fix #21152: fix alignment of lyrics in 1.3 scores
fix tests
Merge pull request #359 from ChurchOrganist/AeolusUpdate

Change Aeolus default to Equal Temperament
Merge pull request #360 from mgavioli/preferences_crash_new_installation

On a new installation, "Preferences" crashes
Improving dot width detection
Merge pull request #367 from mgavioli/Fix_21110_gliss_text_on_wavy_line

Fix #21110 - text on glissando wavy line