Merge pull request #525 from proski/master

Git related patches

Thank you.
I will have to look into the code again soon, because it is not general enough (too tied to thinking about Git only in terms of the Frescobaldi application while it should actually be used for managing LilyPond projects...). I think your improvements will be helpful there too.
typo in changelog

Closes #526
comment out object editor for 2.17 release
make object editor and audio export hidden in non-git releases
as per issue #514
activate new mainwindow, fix #314
a new settings option: enable experimental features
use "experimental features" pref in some places
document new experimental features feature
pot and nl.po update
change Nederlandese into Olandese
italian update by Federico Bruni
add argparse to the list of included modules in windows standalone build