Work in progress for chord symbol spacing.

This expands the containing segment to allow space for the chord symbol.
Further work required to allow a chord symbol to overlap segments that
do not have their own chord symbol.
Allow harmony to span multiple segments.

Also add a style setting for minimum chordname spacing.
Barlines: span attributes were not read back correctly from file.

Probably a left-over from the switch to XmlReader.
Merge pull request #261 from mgavioli/BARLINES_read_span_attributes

Barlines: read span attributes
TAB: with "stems beside staves" option, slashes (for slashed minims) and dots were in some cases positioned wrongly.
Merge pull request #263 from mgavioli/TAB_fix_dots_and_slashes_in_stems_beside_staves

TAB: fix dots and slashes in stems beside staves
change map iterators to auto
use system font to display the UI
fixes for workspace; some palette tweaking
Restore 1.3 behaviour of Space for harmony

Space/Shift-Space will now stop at the next beat, note, rest or chord.
TAB: stems beside staves were wrong with some combinations of parameters and with multiple voices.
Merge pull request #266 from mgavioli/TAB_fix_stems_beside_staff

TAB: fix stems beside staff
Merge pull request #265 from softins/chord-navigation

Restore 1.3 behaviour of Space for harmony
Fix #20488: time sigs are not created for TAB staves.

If "Show time sigs" is turned on for TAB's, no tiem sig is shown as the time sig element is not there.
Merge pull request #267 from mgavioli/Fix#20488_TAB_time_sigs_not_created

Fix #20488: time sigs are not created for TAB staves.
goto/label is evil
first commit of new instruments.xml
align checkbox with other controls in inspector
Fix #20499: time sig not correctly laid out after some changes.
Merge pull request #269 from mgavioli/Fix_#20499_timesig_layout

Fix #20499: time sig not correctly laid out after some changes.