GSoC 2020: Measure repeats for Mu3

[Jojo-Schmitz]

Backport of musescore#6365

Resolves: #438

• Re-enable NOBREAK with fixes and new functionality

  • Fix #279071: "Don't Break" element creates hole at end of system
  • Allow more than two measures to be grouped
  • Allow adding/toggling NOBREAK by clicking palette
  • Rename to "Group Measures"
  • Adjust placement of break symbols
    Co-authored-by: MarcSabatella marc@outsideshore.com

  commit 1, plus some includes cleanup and fixing some clazy warnings

• commit 2 is just about some Mu4 code style stuff which doesn't apply to Mu3, so let's skip it

• Fix #10220: Replace RepeatMeasure with MeasureRepeat, add subtypes 1/2/4

  • Draw with font symbols instead of QPainterPath
  • Automatically group measures and delete contents when adding MeasureRepeat
  • Hide rests by making measures (per MStaff) aware if they are part of measure repeat group
  • Keep measures and element in sync at all times by handling (preventing/warning/special-casing) many user actions
  • Add style options for numbering consecutive one-measure repeats

  commit 3, plus some includes cleanup and fixing some clazy warnings

• MusicXML import/export and (probably) Guitar Pro import MeasureRepeats
  commit 4 and fixing some clazy warnings

• Add/update tests for MMRests and MeasureRepeats
  MMRests:

  • Add vtests for old-style (all fonts), h-bar thickness and margin (Bravura)

  MeasureRepeats:

  • Add script tests for adding, cutting/copying with partial group selected, pasting into group, repeating selection from before group, executing split/join/insert/delete measure commands, adding repeat barlines, and adding time signature
  • Add mtests for parts, MIDI, and MusicXML import/export
  • Add vtests
  • Update ref files

  commit 5 ( I might better integrate them into the other commits as needed though)

• commit 6 is about Additional changes needed after rebasing, shouldn't apply here, so let's skip it too

[Jojo-Schmitz]

Possibly needed other PRs and tasks:

• Enable testLocalTimeSig14
• Fix semi-infinite loop in PlaybackModel (and an assertion) when opening a certain MusicXML score musescore/MuseScore#23339, commit 2
• Don't clone "no break" items to parts musescore/MuseScore#21216
• Don't create single-measure multi measure rests in multi measure repeat measures musescore/MuseScore#21015
• measure_repeats_and_dynamics musescore/MuseScore#20598
• Repeat measure number positioned correctly on all staves musescore/MuseScore#19356 (apparently indeed needed, see add 2 bars and 4 bars repeat #438 (comment))
• Implement playback for multi-measure repeats musescore/MuseScore#15952 (?)

[Jojo-Schmitz]

the mtests and vtests failures are (mostly) due to crashes, so more work to do...