Errors in our Api-Docs

As you might know, KDE uses EBN to check for errors in the code and in
the dox. As libavo is now in Kalzium EBN also checks libavo :slight_smile: Ok, I
already fixed most of the code issues but many dox issues remain
unfixed. In case you have a few spare minutes why don’t you fix

Carsten (now going to fix more code issues)