make radio button for min / avg / max growth value be pushed into which_growth in the DB for bill_type row, then also delete estimated bills for that bill_type, and then calling /bills, causes the estimated bills to be filled back in based on the new chosen growth model

db.py

@@ -278,6 +278,16 @@ def get_bill_types():
     conn.close()
     return bt
 
+def use_growth( bill_type, which_growth ):
+    conn = connect_db(False)
+    cur = conn.cursor()
+    cur.execute( f"update bill_type set which_growth = '{which_growth}' where id = {bill_type}" )
+    # okay, new growth type being used, delete old estimated bills are recreate them
+    cur.execute( f"delete from bill_data where estimated=1 and bill_type = {bill_type}" )
+    conn.commit()
+    conn.close()
+    return
+
 def get_bill_freqs():
     conn = connect_db(True)
     cur = conn.cursor()