self source no longer meta

I have decided to change this tag from Meta to a Source, following in the same vein as the original song tag. Before, if you were to tag a self sourcing video that was not multisource, it would still tell you the work was missing a source, even though it wasn't. Now this will not happen, and, in my opinion, it is nicer to have the tag with the rest of the sources in a list rather than with the Meta tags.