Fix Weather Packet Parsing

Unroll proposed weather packet parsing fixes for PR#81 (Issue rossengeorgiev#80).

Course and Speed are ignored by parse_data_extentions() by when either value is '000'.  I.e. 000/000 is considered not relevent an is ignored.  When either value is 000, course or speed is set to None.

It is possible for a weather report to have a speed of 0, meaning no wind.  This should still be captured as it's relevent for a weather report.  Course can also be 0, since some weather stations will report 0 for direction when speed is also 0.

The core of the issue is that parse_data_extentions() ignores course and speed as noted above, AND it trims the course/speed from the body string.  parse_weather_data() still looks to parse course/speed, but cannot when it's been removed by parse_data_extentions().  This change duplicates the contents of "body" so both parse_data_extentions() and parse_weather_data(body) have the appropriate body to parse.

aprslib/parsing/position.py

@@ -62,27 +62,18 @@ def parse_position(packet_type, body):
     if parsed['symbol'] == '_':
         # attempt to parse winddir/speed
         # Page 92 of the spec
+
+        # Duplicate body since parse_data_extentions() trims it and chops off
+        # part of the weather packet that parse_weather_data() expects
+        weather_body = body
+
+        # Parse extensions
         body, result = parse_data_extentions(body)
-        wind_speed = result.get("speed")
-        wind_direction = result.get("course")
+        parsed.update(result)
 
         logger.debug("Attempting to parse weather report from comment")
-        body, result = parse_weather_data(body)
-        if wind_speed:
-            result.update({
-                'wind_speed': wind_speed * 0.44704,
-            })
-        elif wind_direction:
-            # Since result.get("speed") now returns None if speed is 0,
-            # set wind speed as zero if wind direction has also been reported
-            # This is consistent with the behavior in 0.7.1 and earlier.
-            result.update({
-                'wind_speed': 0,
-            })
-        if wind_direction:
-            result.update({
-                'wind_direction': wind_direction,
-            })
+        body, result = parse_weather_data(weather_body)
+
         parsed.update({
             'comment': body.strip(' '),
             'weather': result,