Fix #22167: graces in TAB's collide with main chord.

Fixed and also improved grace stem length for TAB with stems beside staff.
fix #23366

At least a first batch
Merge pull request #523 from Jojo-Schmitz/fix.orig.texts

fix #23366
Merge pull request #522 from mgavioli/Fix_22167_TAB_graces_collide

Fix #22167: graces in TAB's collide with main chord.
fix #23369

Adds support for "/" within chordnames if the portion after the "/" is
not convertible to tpc and hence not a valid bass note.  This allows for
C6/9 to be rendered as such.  I look at the *last* slash when deciding
how to proceed, so C6/9/E is handled correctly.
Merge pull request #524 from MarcSabatella/23369-slash-in-chord

fix #23369
fix #23366 2nd batch

Almost certainly a 3rd batch to follow, for many of the CamelCase
strings
Merge pull request #525 from Jojo-Schmitz/fix.orig.texts

fix #23366 2nd batch
Fix #23371 : in TAB's grace chords are not fretted at all or fretted incorrectly.

Since the grace chords have been moved from a parent segment of their own to a parent chord, the fretting algorithm no longer 'sees' them correctly.

Fixed by extending the fretting algorithm to deal with chords not belonging to segments.
Merge pull request #528 from mgavioli/Fix_23371_TAB_grace_chords_fretted_wrongly

Fix #23371 : TAB - grace chords fretted incorrectly