Merge pull request #193 from PeterBjuhr/master

Pull request for Issue #191
credits
use elif
pot/po/nl update
fix markup quick remove
also show submenus in keyboard shortcut settings pages, not only flat lists for the main menus.
simple import using musicxml2ly see Issue #194
Merge pull request #195 from PeterBjuhr/importxml

simple import using musicxml2ly see Issue #194
move importXML to file_import/musicxml.py

group functionality and probably a shared dialog,
use lowercase module names.
when user cancels dialog, stop import
new method to get commandline for lilypond-tool
use new toolcommand() method
let musicxml import use the lilypondinfo
keep using the full path for the importfile.

also, dont use os.chdir (it changes workdir globally)
use subprocess.Popen (although later we will use QProcess and have a "live" log window")
let musicxml2ly write to stdout and then set the text and url of the document, but not write it to disk yet
use abscommand() in music preview as well
use busy cursor during musicxml import
add stdout() and stderr() methods to Job, to get output from the process afterwards.
add the option to Log to restrict output display of messages to certain types
run the engraver on the newly created document