The chameleon TAL engine never really got used much in Roundup AFAIK. The fact
that chameleon used a different default for the expression evaluation (python not path)
was an issue.

z3c.pt from the zope foundation uses chameleon on the back end but is a wrapper to provide
compatibility with templates originally written for zope.

This might be a way to get a better performing engine since our vendored zpt code
should be updated (issue2551324).

If we add this should be deprecate chameleon??