Don't touch window title before an OSC is received.

Fixes the "window title being clobbered" issue raised in issue 137.

Signed-off-by: sqweek <sqweek@gmail.com>

Closes #380. Closes #137.

src/terminal/terminaldisplay.cc

@@ -56,7 +56,7 @@ std::string Display::new_frame( bool initialized, const Framebuffer &last, const
   }
 
   /* has icon name or window title changed? */
-  if ( has_title &&
+  if ( has_title && f.is_title_initialized() &&
        ( (!initialized)
          || (f.get_icon_name() != frame.last_frame.get_icon_name())
          || (f.get_window_title() != frame.last_frame.get_window_title()) ) ) {