Translation DE_de updated + gettext functions

Gettext plural functions T_ngettext and ngettext corrected.
Gettext now also detects that plural strings as plural strings.
Updated gather-messages.sh keywords.
mo's and po's updated
Update gather-messages.sh
del windows line endings
Update show_recently_played.inc.php
Merge pull request #170 from Psy-Virus/develop

Translation DE_de updated + corrected gettext functions