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
remove debug print
some more readme/dev