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"
Merge remote-tracking branch 'origin/master' into import-export-theme
Merge pull request #221 from elmamyra/import-export-theme

add import-export module for keyboard shortcuts and fonts & colors
chlog/pot/po/nl
make app.is_git_controlled() cheaper

dont try every time if the .git directory exists, instead remember the
result of the first call and return that next time.
separate logic