Proposal: Combine Novatel and Unicore Receivers

[bemasher]

Novatel and Unicore receivers use similar message formats. Unicore receivers even produce some Novatel-compatible messages like RANGEB, and several messages containing SBAS data.

It may be useful to combine the two decoders to handle the case where Unicore receivers only respond with Novatel messages for some commands and Unicore with others.

I'd be willing to work on this if this sounds reasonable to others.