This PR should complete the revision of bar line flag managements.
- Make sure single bar line span changes affect both the `_customSpan` and the `_generated` flags.
- Make sure that manually bringing a custom-spanned bar line to default span resets the `_customSpan` flag and, if no other customization is in effect. the `_generated` flag.
- Deleting a measure bar line resets it to default configuration.
- Fix a missing initialization of `Measure::_endBarLineColor` variable.
- To simplify tests and debug, check boxes for the `BarLine::_customSpan` and the `BarLine::_customSubtype` have been added to the debugger dialogue box.
As far as system-initial bar lines are concerned, they were made un-editable by a recent commit (https://github.com/musescore/MuseScore/pull/1300). This PR add a few consistency changes:
- system-initial bar lines do not accept drops;
- they are not saved to score output files and are ignored when reading from them;
- their internal `_customSybtype` and _customSpan` flags are always false;
- they do not show up in the Inspector (if a system bar line is selected, the Inspector remains blank)
This PR DOES NOT include the special system-initial double bar management recently discussed. This will be part of a specific PR in the next days.
Together with previous PR's, this should ensure that:
- bar lines are written to a score output file only when some customization is in effect which cannot be reconstructed when reading back;
- any measure bar line can be edited;
- any measure bar line user edit is saved, written to the score file and read back properly;
- no system bar line edit is possible.
There are some inconsistencies in the current management of bar line `_generated` flag and user-modified type:
- Bar lines created by the New Score Wizard are flagged as non-generated, as well as bar lines of measures manually **appended** by the user, while bar lines of measures **inserted** are flagged as generated.
- If a generated bar line is individually changed of typed, it remains flagged as generated, it is not saved and the change is lost upon saving and re-loading.
- The management of the internal flag `BarLine::_customSubtype` is not always consistent.
- The `Measure::_endBarLineGenerated` flag was not always restored properly by undo.
This PR introduces the following fixes:
- The `_generated` flag is consistently used for bar lines whose type can be reconstructed from the context and then do not need to be saved to the output file.
- Normal bar lines are **always** created as generated: initially created by the Wizard, manually appended or inserted.
- Bar lines with custom type (i.e. different from the type which can be expected according to the bar line context) are always flagged as non-generated, ensuring the custom type is written to the output file.
- The `Measure::_endBarLineGenerated` flag is stored by `ChangeEndBarLineType()` and restore upon undo.
- Some test reference scores, based on the inconsistent bar line `_generated` flag, have been uniformed.
Notes:
- Tests about measure (and then bar line) appending, inserting and relative undo's are already included in the `tst_parts` test suite.
- Some inconsistencies remain in the management of custom bar line span and of system-initial bar lines: for the sake of simplicity, they will be dealt with in separate PR's.
