Item12675: Resolve taint issue in normalizeWebTopic

Replace use of a character class with a non-grouping or.  Resolves the
tainting issue, but it's about 4% slower per Benchmark

git-svn-id: http://svn.foswiki.org/branches/Release01x01/core@17226 0b4bb1d4-4e5a-0410-9cc4-b2b747904278