Non-GPS Messages

[hpuhr]

According to https://anavs.com/knowledgebase/nmea-format/ there are additional message formats:

• GP for GPS only solutions
• GL for GLONASS only solutions
• GA for GALILEO only solutions
• GN for multi GNSS solutions

The GPS messages are supported, while the others are not, limiting the usability of the library.

I'll do a fork and add the other formats (as long as I have test data for them) as described in #4 .

And do a pull request later.

[hpuhr]

Should be fixed, is in pull request #23

[maladzenkau]

Hi, @hpuhr.
Thank you for your fixes. I have also added support for GLL messages in pull request #25, alongside your changes.