Minor spelling fix.
Correct the terminology used in the value description? Both <http://gpsd.berlios.de/NMEA.html#_mwv_wind_speed_and_angle> and <http://www.tronico.fi/OH6NT/docs/NMEA0183.pdf> state that the "T" value means "True" not "Theoretical". It is assumed they don't disagree with the official, closed specification.
Minor typo fix.
Minor white space fix.
Add test for existing `MWV` sentence parser with supplied sample data.

Conflicts:
	pynmea2/test/test_types.py
Add (sub-optimal) support for generic proprietary sentences. This means we can easily skip any proprietary sentences without causing the parser to barf. The implementation is sub-optimal because I prioritised minimising the changes to the existing `parse` routine.

Conflicts:
	pynmea2/test/test_types.py
Re-add test accidentally removed during cherry-pick.
Change the wording of this comment to remove "tuple" because with the changes in master `data` is now a list.
Merge branch 'mwv-test' into add-xdr-sentence-support
Merge branch 'add-generic-proprietary-sentence-support' into add-xdr-sentence-support

Conflicts:
	pynmea2/test/test_types.py
Add support for XDR sentence parsing. Still requires some additional documentation.

Conflicts:
	pynmea2/test/test_types.py
Don't include the talker in the XDR representation in order to match the other types.
Add documentation on the XDR/transducer-related classes.
Change to use `value` rather than `data` for the name of the field of the Transducer class to avoid confusion with the `data` field of the XDR sentence type class. (Which produces odd errors if you mistake an instance of one class for the other. *cough*)
We no longer need to convert this into a list from a tuple because master has changed to use a list rather than a tuple.