This patch reworks all the packet processing to use the new
Packets objects. Nuked all of the messaging classes.
backwards incompatible changes
all messaging.py classes are now gone and replaced by
packets.py classes
This patch completely refactors and simplifies how the clients
are created and used. There is no need now to have a separate
KISSRXThread. Since all the custom work for the KISS client is
encapsulated in the kiss client itself, the same RX thread and
callback mechanism works for both the APRSIS client and KISS Client
objects. There is also no need to determine which transport
(aprsis vs kiss) is being used at runtime by any of the messages
objects. The same API works for both APRSIS and KISS Client objects