Updates rtefcst.Route to NautAngle, bbox

Updates Route class to use objects.NautAngle instead of LatLon; adds two named
tuples, BoundingBox and Position, to sl.lib.objects; adds full_circle() method
to NautAngle; forecast related test are commented out unitl xray interface
becomes available in sl.lib.tinylib
Merge pull request #9 from ms8r/latlon

Updates rtefcst.Route to NautAngle, bbox