Make difficulty 128 bit instead of 64 bit

Based on Boolberry work by:
  jahrsg <jahr@jahr.me>
  cr.zoidberg <crypto.zoidberg@gmail.com>

tests/difficulty/wide_difficulty.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+import sys
+import subprocess
+
+python = sys.argv[1]
+py = sys.argv[2]
+c = sys.argv[3]
+data = sys.argv[4]
+
+first = python + " " + py + " > " + data
+second = [c, '--wide', data]
+
+try:
+  print('running: ', first)
+  subprocess.check_call(first, shell=True)
+  print('running: ', second)
+  subprocess.check_call(second)
+except:
+  sys.exit(1)
+