more packet trickery

Pushed some more changes to libusipp git:

 o 802.11 stuff for better frame handling (wanna chat
   about wireless firmware exploits? Come talk to me [1] :)
 o No longer needing libdnet for ARP objects, which means
   that ARP and EAPOL is now also available on OSX. So since
   now you as well bypass your favorite 802.1x Switch-Nazi with
   your oh so cool iShit

[1] Me also interested in any patches already existing to
    use the radiotap pflags channel element for TX (e.g.
    setting TX channel per packet. the channel flag only seems
    to notify about RX channel for captured packets and is
    ignored for transmission?).

I know: the libusipp API is not very stable, but I dont mind.
All my github projects requiring libusipp properly build with
latest pull.