Fix weird typo

Not sure what happened here, but obviously ADEND_ARG should have been TVHEADEND_ARG.
Completely clueness how this has come about.
Merge pull request #2101 from dagwieers/tvheadend-typo

Fix weird typo
Merge remote-tracking branch 'upstream/master'
Updated Copyright-Info for 2013

NO FUNCTIONAL CHANGES!!

This is a huge pull. Think about pulling this, but I recommend it to
provide further protection of your rights!!