Rename Tablature class to StringData

Refactoring the following names:

Classes:
Tablature => StringData

Member variables and methods:
Instrument::tablature() => stringData()
Instrument::setTablature() => setStringdata()
InstrumentTemplate::tablature => stringData
InstrumentData::_tablature => _stringData
InstrumentData::tablature() => stringData()
InstrumentData::setTablature() => setStringData()

There is no change in logic or program behaviour, only renaming.
* Fix Guitar Pro test ref. file.

* Replace "Tablature" with "StringData" in instruments.xml

* Remove support for "Tablature" tag from instrtemplate.cpp (but keep it in instrument.cpp for compatibility with existent 2.0 scores)
Merge pull request #475 from mgavioli/Rename_Tablature_class_to_StringData

Rename Tablature class to StringData
Adds an "Early music" instrument group which includes instruments used in European music before XVIII c. (many of them not in other groups)

As the very concept of "early music" is foggy and there is always a margin of subjectivity, it may be improved and also easily argued upon! :)

(I also added the 7th string to the viola da gamba)
fix #22308: Changing shortcuts does not work
fix #22308: Changing shortcuts does not work
move cursor to next chord when stacking notes, skip rests in repitch mode
fix for cautionary clefs
minor ui improvement, remove border around palette and inspector
Merge pull request #476 from mgavioli/Early_music_instrument_group

Add an "Early music" group to instruments.xml
fix #22711: Dropped frame or barline not showing in continuous view
fix regression: musicxml export of clef
fix mm rest layout
fix #22026: Instrument not completely removed from part
fix for measure rest layout
fix #22740: removing instrument causes crash
add visual tests 'vtest'
add fmrest-1 to vtest
add image compare to vtest
stafftext.ui update

Finally managed to sort this out! Aeolus stop list buttons are now of a
uniform colour and Tremulants have green text and couplers have red.
Had to resort to hacking the file in Notepad++ to get the width and
height back to the original values -Qt Designer inisits on increasing
the width to 1134 and then won't let you change it.