generic: remove the dlna stuff and add codec container handlers

This patch removes the dlna stuffs from generic plugin and for backward
compatibility we have introduce some container and codec handlers so we
can result in the same identifiers as the other plugins, if a handler
is not found we go with what we can extract from the file using the
libavformat api.

The mp4 codec implementation lacks on some profiles/levels parsing by
no a smaller subset - not a minimal, but a smaller subset.