Add Degree Symbol to Track Value

Add the degree symbol to the "Track:" value in the plane details
section.
Change the Background Color for a Plotted Plane

Changed the background color for a plotted plane in the planes table to
something that was more easily visible.
Improve map display layout and styling
Don't restrict sidebar width
Check if bit correction happened before bailing out due to a bad CRC.
Fix --gain with fractional gain values.
Reject out-of-range latitudes when doing CPR decoding.

If a CPR message with an undetected error is received this can produce out-of-range results for latitude.
e.g. even latitude of 78000, odd latitude of 0 produces a latitude index j=35 and rlat0 = 213.
Prefer to use global CPR decoding where possible.

There is a danger in always using relative decoding where possible.
If there is an undetected error in the first pair of messages received,
then global CPR decoding will give a bad position, and subsequent
relative decoding will just walk around near that bad position even
though many error-free pairs of odd/even messages may have been received.

The first pair of position messages also tends to be the most error-prone, as
they are usually received at the extreme edge of receiver range.

(I see this happen at least once a day in practice)

So, instead, prefer to use global decoding when we have sufficiently recent data.
With recent data this should always be as good as relative decoding, and it
avoids getting stuck with bad data for long periods of time. If we don't have
enough recent data for a global solution, fall back to relative decoding.
Add --stats-every <secs> option.

Periodically displays and resets stats.
Useful for unattended operation.
Add stats for number of sample blocks processed and dropped.
Don't output message reception time in SBS format for remote messages.

For remotely received messages that have a mlat timestamp, we have no
useful way of turning that timestamp into a wallclock timestamp, so
don't try, or we'll just produce wildly wrong results (_days_ in error)
Move the stats reset strictly after stats display, so the total message count is shown correctly.
Merge pull request #39 from mutability/fractional-gain

Fix --gain with fractional gain values.
Merge pull request #40 from mutability/discard-bad-cpr-latitudes

Reject out-of-range latitudes when doing CPR decoding.
Merge pull request #29 from tslocum/bettermap

Improve map display layout and styling
Merge pull request #27 from ddeitterick/format_track_field

Add Degree Symbol to Track Value
Merge pull request #28 from ddeitterick/change_plotted_plane_table_bg_color

Change the Background Color for a Plotted Plane
Undo Parts of Pull request #29

The table sizing doesn't seem to work in M$ IE8 and IE9.
Read Files are binary

When replaying recordings, the read files are binary, so the file open
needs to reflect this so that spurious end of file characters aren't
misinterpreted.
Merge pull request #41 from mutability/skip-remote-timestamps

Don't output message reception time in SBS format for remote messages.