Merge pull request #6 from pawelulita/master

Bugfix #584603 (Filename processing turns good chars to _)
update appdata screenshot to wide screen.
remove debug print.
bump version to 2.1.2
Merge branch 'master' of git@github.com:kassoulet/soundconverter.git
Merge branch 'master' of https://github.com/kassoulet/soundconverter