Temp
Broke a whole lot of stuff. New HDLC deframer.
Added PDU to NMEA block.

THIS BRANCH WILL NOT RUN FOR YOU. See "TODOs".

New features:
* Properly splits NMEA sentences below the 82-char NMEA 0138 limit
* Properly pads ASCII NMEA data to 6-bit boundaries
* Uses fancy Gnuradio PDUs to pass data packets around
* HDLC deframer should be useful for any HDLC-framed data with minor
  modification (max/min pkt length sanity checks are hardcoded)
* Entire AIS receive chain is blocked out in GRC
* Hopefully a *lot* more sensitive than the original

TODOs:
* Update main application to use the new PDU structure
* Bring MSK timing recovery block into Gnuradio (is currently private)
* Bring MSK correlator into Gnuradio and fix its issues
* Bring GRC block for square&FFT freq sync into AIS
Properly assign total # of fragments.
Use deframer & MSK blocks from latest Gnuradio
Remove freq sync for now.
Update main application to work with new MSK blocks. Still using
non-free freq sync.
Using AIS version of sync
Remove cruft.
Remove dependency on unused package.
Update CMakeLists to require 3.8
Merge branch 'master' of github.com:bistromath/gr-ais

Conflicts:
	CMakeLists.txt
	grc/CMakeLists.txt
	include/ais/CMakeLists.txt