remove outer loop in sortData() because only need to take care of the data in the set_key

Remove outer loop in handling_data.sort_data() because only need to take care of the data in the set_key: #30 (closed) - 3

Make sort_data() to really sort traces according to startTmEpoch: #30 (closed) - 28

sohstationviewer/model/mseed/mseed.py

@@ -303,4 +303,4 @@ class MSeed(DataTypeModel):
                     self.trackInfo(
                         f'Read {count} waveform files', LogType.INFO)
 
-        sortData(self.waveformData)
+        sortData(self.waveformData[staID]['readData'])