Move to_string(MessageType) to SkyTraqBin.cc.
Reorder enum's to be the same order as found in the docs.
Throw exception instead of returning empty string from to_string(MessageType).
Add std::to_string() and operator<<() overloaded functions for all enums.
Remove two done items from todo list.
Use Boost.Date_Time to represent dates and times in SkyTraq binary messages.

Untested.
Use boost.date_time objects in NMEA-0183 classes.

Untested.
The RMC sentence contains a two-digit year number. For now I just add 2000. Maybe in the future it should have some heuristic to handle files from pre-2000.
Remove "use boost.date_time" from todo list.