implement StaffText and SystemText for parts
updates for Glissando
updates for Arpeggio/Tremolo in parts
Jump and Marker elements for parts
link beam properties to parts
link time signature changes to parts
Figured bass: Continuation lines end right after the last ChordRest of the FiguredBass element.

Previously, they were drawn for the whole duration of the FiguredBass element (stopping right before the next segment).
Merge pull request #237 from mgavioli/Figured_bass_cont-line_cleanup

Figured bass: Cont. lines clean-up
make custom palettes translatable