Disable window title reporting by default, since it's a security

Disable window title reporting by default, since it's a security
hazard. I considered removing it completely, but I can't rule out
the possibility of an OS that actually takes security of its
terminal devices seriously, and which might be able to make sensible
and safe use of this feature.

git-svn-id: http://svn.tartarus.org/sgt/putty@3103 cda61777-01e9-0310-a592-d414129be87e