add addSchemeData and import/export methods
add import/export methods
replace add/remove buttons by a menu with add, remove, rename, import
and export actions
add import_export module
Merge remote-tracking branch 'upstream/master' into import-export-theme
remove a "print"
preview-mode help: comment about -ddebug-layout
preview-doc: Review "Engrave (Preview)" page
simple module to help debugging frescobaldi
preview-mode: Rename configuration variables

Make them more consistent.
Noticed the need for it when writing documentation
preview-doc: Configuring Debug Modes

Add description how to configure Debug Modes through
configuration variables.

Now I think this is straightforward enough so we don't
need to clutter the GUI with yet one more Preferences page.
touchup debug.py, more can be done but it is already nice.
Merge pull request #214 from PeterBjuhr/master

Improvements on the musicxml import
Merge pull request #215 from uliska/preview-doc

Finish documenting Preview Mode
dont keep busy cursor while displaying error message
cant have empty translatable strings
simpler help doc text (remove text thats not necessary), -nd → --nd
no unneeded markup in translatable strings
nitpicks
pot/po/nl