* doc/syntax/mutt.nanorc: Include Benno's awesome signature
          matcher, modified slightly to also work for quoted sigs.
        * doc/syntax/default.nanorc: Be far more gentle with something
          which affects every file which doesn't match another syntax, and
          the user may not be able to override if their distro turns on
          highlighting by default.\



git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@4929 35c25a1d-7b9e-4130-9fde-d3aeb78583b8