Log Message:
Update wistumbler2 to 2.00pre7, sent by the Author pancake in private
email, this also closes PR pkg/24172 by Noud de Brouwer.

Changes:

        - Wifi rate patched.
        - Add background sniffer.
        - Add pthread, for non-blocking GUI.
        - Autodetect ifaces (up/down) on the fly (threads).

While here switch this package to use buildlink3.