seeyou: Moved runway parsing code to parse_runway() method
seeyou: Moved frequency parsing code to parse_frequencies() method
seeyou: Pass fields directly to parse_coordinates()
tests: Added SeeYouReader.parse_runway() tests
seeyou: Added support for statute miles and nautical miles for runways
seeyou: Extracted parse_altitude() method
seeyou: Added float and feet support to parse_altitude() method