Blender Git Loki

Fix (unreported) Append/link code: All library datablocks could end with same name.

This was broken since ages I think, did not really hurt since we usually never use libs' names
to access them. Rather bad behavior however, breaking a ground rule of our ID system!

And no real reason to add new libraries to new (split) Main at all, libraries are
never considered linked datablocks, which means they should always be in 'main' Main->library list.

Not a regression, but should be included in 2.76 imho.