[FIX] Avoid catastrophic error display for some sorting value

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@50798 b456876b-0849-0410-b77d-98878d47e9d5
[FIX] sefurl: Missing sefurl for backlinks

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@50799 b456876b-0849-0410-b77d-98878d47e9d5
[FIX] Correctly validate plugin names with numbers which were valid in Tiki6 and Tiki9, so these don't fail on upgrades to Tiki 12 (thanks lph)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@50800 b456876b-0849-0410-b77d-98878d47e9d5