Reimplement --securerandom

Seeds should be reproducable without the flag passed, and unreproducable with the flag passed.
With --securerandom, generate a 9-char alphanumeric string to use to make filenames differ.

DungeonRandomizer.py

@@ -3,7 +3,7 @@ import argparse
 import copy
 import os
 import logging
-import random
+import RaceRandom as random
 import textwrap
 import shlex
 import sys