Initialise LAT/LON to zero (0.0) in the parser

If there is no LAT/LON data often GC will set really small numbers
to LAT/LON which the map functions will try to map.

Fixes #522

src/TcxParser.cpp

@@ -78,6 +78,8 @@ TcxParser::startElement( const QString&, const QString&,
         power = 0.0;
         cadence = 0.0;
         hr = 0.0;
+        lat = 0.0;
+        lon = 0.0;
         //alt = 0.0; // TCS from FIT files have not alt point for each trackpoint
         distance = -1;  // nh - we set this to -1 so we can detect if there was a distance in the trackpoint.
     }