Enables pasting FiguredBass elements.

To be sure the element is pasted into the right track, the track is set again after reading the element.
This also affects Dynamic, Symbol, FretDiagram, Marker, Jump, Image, Text, StaffText, TempoText.
TAB: initial support for multiple voices.

Note fretting in one voice takes into account frets in other voices.
Stems, beams, etc are NOT adjusted yet.
Merge pull request #241 from mgavioli/TAB_initial_voice_support

TAB: initial support for multiple voices.
fix arpeggio regression
fix too wide layout spacing
do not write control chars in XML
fix #18618 : File suffix has to be entered when saving snapshot
fix #13577 : Drag-selected lasso rectangle remains
fix #19129 : Small note in chord is detached from stem
Merge pull request #244 from Soerboe/fix19129

fix #19129 : Small note in chord is detached from stem
fix bad alignment of small notehead in tablature
Merge pull request #242 from Soerboe/fix18618

fix #18618 : File suffix has to be entered when saving snapshot
Merge pull request #243 from Soerboe/fix13577

fix #13577 : Drag-selected lasso rectangle remains
Fix #19931: Use native file dialog on windows and mac, and qt file dialog on unix
exclude more control chars from XML write
replace all subtype()/setSubtype() Element methods
new subType() Element method for selection gui
fix mtest
fix #20331 Attempting to move a measure number results in a crash
allow multi selection of same element type in inspector, part1