Feature Request: Add "Route" functionality to PING robot

When doing PING (or trace) to determine routing, it would be handy to be able to specify what route the ping (or trace) should follow. There is an example implementation of this on 2:460/58. Sending that system (ping@2:460/58) a ping request, replies with the correct ping response, but adds the following:

---------- Help ------------------------------------------------------------
  Also, You may use the following commands in the Subject line:
  %RouteTo: <3D_address> - The Ping robot reply will be routed via
                           this node. It MUST be my password-protected link.
  %Links                 - Get the list of my password protected-links.
  -------- Example ---------------------------------------------
  From: BoonDock                        4:920/69
  To  : Ping                            2:460/58
  Subj: %RouteTo: 2:292/854
  --------------------------------------------------------------
   - The answer to this message will be routed via 2:292/854.
----------------------------------------------------------------------------

The addition of the %RouteTo: functionality would be fantastic.