fuzzed version of testStress()

testStress.cpp

  while (!std::cin.eof() )
    {
      // pick a random ledger history
      std::string curr = "";
      char depth = getBits( maxDepth );
      char offset = 0;
      for(char d = 0; d < depth; ++d)
        {
          char a = offset + getBits( maxWidth );
          curr += a;
          offset = (a + 1) * maxWidth;
        }
      
      // 50-50 to add remove
      if(getBits(2) == 0)
        t.insert(h[curr]);
      else
        t.remove(h[curr]);
      
      assert( t.checkInvariants() );
    }