add a button to recalc bills by removing all esimated bills and rebuild them

db.py

@@ -395,3 +395,12 @@ def save_ui(data):
     conn.commit()
     conn.close()
     return
+
+
+def delete_estimated_bills():
+    conn = connect_db(False)
+    cur = conn.cursor()
+    cur.execute( "delete from bill_data where estimated=1" )
+    conn.commit()
+    conn.close()
+    return