Interface for single Textpack string.

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5529 2fea6a4d-a838-0410-917b-93a53c48e9d2
HTML in comments needs to be encoded.

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5530 2fea6a4d-a838-0410-917b-93a53c48e9d2