Don't relay on regex when resolving classes in the container

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5761 2fea6a4d-a838-0410-917b-93a53c48e9d2
Remove regular expression usage from container.

Performance optimisation.

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5762 2fea6a4d-a838-0410-917b-93a53c48e9d2