Fix calculation of cdd statistic

For specific ciphertexts the wrong initialization of a variable would
insert undefined state into the internal logic of the 'cdd' statistic.
This lead to many thrown (and catched) excpetions, which decreased the
performance significantly.

An example of such a ciphertext is: 'ooooo' or other sequences of the
same letter.

Author: MaikBastian

cipherTypeDetection/featureCalculations.py

@@ -359,7 +359,7 @@
         var i,j,k;
         var max,sum;
         var index,dif,long_corr,short_corr;
-        max = 0;
+        max = -1;
 
         for (j= col;j<key_len;j++) {
         long_corr = short_corr = 0;