bugfix: pystring::translate works when using both table + deletechars

Fixed bug in translate, documented in github issue #3, and previously at
http://code.google.com/p/pystring/issues/detail?id=4

Author: jeremyselan

pystring.cpp

@@ -766,7 +766,7 @@ namespace pystring
         {
             if ( trans_table[ (int) str[i] ] != -1 )
             {
-                s += table[ s[i] ];
+                s += table[ str[i] ];
             }
         }