Implement a dialog to plot and export GPS data

Create a dialog with buttons to plot and export GPS data.

Show information about a GPS data point when user clicks on it.

#19 (closed)

tests/test_model/test_mseed/test_gps.py

 import unittest
 import math
 
-from sohstationviewer.model.gps_point import GPSPoint
 from sohstationviewer.model.mseed.mseed import MSeed
 
 
@@ -164,5 +163,3 @@ class TestExtractGPSPointQ330(unittest.TestCase):
         self.assertEqual(result.latitude, 0)
         self.assertEqual(result.longitude, 0)
         self.assertEqual(result.num_satellite_used, 0)
-
-