Added code to read the text within frames in accessibleExtraInfo(),
but also fixed the navigation to check for a frame
before moving to the next/previous measure.
Because frames will generally have a track of -1,
I also needed to take advantage of the tracking of the current track from a previous commit
so that nagivation continues on the correct track after passing through a frame.
I also needed to be careful to handle the -1.
This fixes a crash that occured during the TBox deconstructor.
When generating an album, there joined scores have their measures cloned into the first score. However, the TBox clone constructor did not allocate a new Text object when performing the clone, but rather only simply copied the pointer address. Hence, when the Album::createScore() would delete the score, that original Text object would be deleted. But then the second time that score was deleted, that corresponding TBox would have _text pointing to an previously-deleted Text object. The solution I've done is to allocate a new Text object during clone.
reformatting, removing some comments that are irrelevant to plugin
framework in a way that DoxyGen should still find them, documenting the
enums and fully qualify all types that are specific to MuseScore,
