[bp/r52316][FIX] filegals: Correct an issue from old upgraded Tikis where users may have more than one user file gallery.
If this is the case, merge the files from the old ones into the new correctly named one and remove the old gallery.

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@52318 b456876b-0849-0410-b77d-98878d47e9d5