traceback: allow providing a local support contact point The extensions blaming code is fine for casual users but pretty terrible for corporate environments that can deploy a large amount of extensions to unsuspecting users. Reports will likely blame a random "innocent" extension (in our case crecord) and the hint in the message will triggers endless debug attempts from the user. We introduce a "ui.supportcontact" option that allow such big company to redirect their users to their own support desk. This disables all extensions blaming and just point people to the local support in all cases.