Make Radar a child class of DatabaseTable

lib/nexrad/radar.py

@@ -1,6 +1,7 @@
 import csv
 import re
 
+from nexrad.db    import DatabaseTable
 from nexrad.coord import Coord, COORD_SYSTEM
 
 """
@@ -40,7 +41,7 @@ def parse(text: str):
 
 RADAR_RANGE = 230000
 
-class Radar():
+class Radar(DatabaseTable):
     __slots__ = (
         'call', 'wban', 'name', 'coord', 'site_elevation', 'tower_height',
     )