improve adif support, look for station_callsign field

hamtools/adif.py

@@ -69,7 +69,7 @@ class Reader(object):
             self.header_present = True
             for field in self._lex(blocksize=1):
                 if field.name == 'adif_ver':
-                    self.adif_ver = Decimal(field.body)
+                    self.adif_ver = field.body
                 elif field.name == 'eoh':
                     break
         self.bookmark = flo.tell()

hamtools/geolog.py

@@ -174,6 +174,9 @@ class Log(object):
                 pass
             self.qsos.append(qso)
         if self.qsos:
+            qso = self.qsos[0]
+            self.callsign = qso.get('station_callsign', None)
+            if not self.callsign:
                 self.callsign = qso.get('operator', None)
         return self