Fix ublox plot in case where no explicit reference position is given
Remove command line options left over from dgps_test that arent applicable here
add a little class that translates NMEA packets to ublox-like structures.  this means that NMEA GPS receivers may be used for the corrected and uncorrected rovers (but not beacon at this stage)
Fix bug in the save of the satellite residuals
guard the satellite position functions against incomplete ephemerides having been loaded
Correct scales in the satellite log plotter output windows
Make the ublox plot output lines transparent to make the trajectories easier to read when they loop back over themselves (very often if you have a static receiver!)
Wire in the nmea option for receivers to the ntrip dgps test script
Add a script to calculate single and dual receiver statistics for comparison
Merge branch 'master' of https://github.com/benizl/pyUblox

Conflicts:
	satlog_plot.py
Merge branch 'master' of https://github.com/benizl/pyUblox
satlog_plot: Add support for plotting of trimmed average
RTCMv2: Add support for trimmed averaging over history period