Fix #20488: time sigs are not created for TAB staves.

If "Show time sigs" is turned on for TAB's, no tiem sig is shown as the time sig element is not there.
Merge pull request #267 from mgavioli/Fix#20488_TAB_time_sigs_not_created

Fix #20488: time sigs are not created for TAB staves.
goto/label is evil
first commit of new instruments.xml
align checkbox with other controls in inspector
Fix #20499: time sig not correctly laid out after some changes.
Merge pull request #269 from mgavioli/Fix_#20499_timesig_layout

Fix #20499: time sig not correctly laid out after some changes.