Don't try to use Titlecase wrapper if not defined

Don't try to use Titlecase wrapper if not defined

Don't try to call the function passed from Lingua::EN::Titlecase
function if the tc variable is undefined.

This avoids having blank titles when the template is used in an
environment where EGWeb isn't passing the function to the templates.

Signed-off-by: Jeff Godin <jgodin@tadl.org>