#367: unallowable filter names

[domtheknight]

If you attempt to use an bad format in a filter name (such as a comma or a #, probably other characters as well), a long error message beginning "[Error: invalid group name at
/home/dw/current/cgi-bin/DW/User/Edges/WatchTrust.pm" appears at the top of the page.

ETA 3/5 - commas and hashes both work; logic should now match LJ's logic exactly.