Fixed bug number 2914467 submitted by Michael Krelin. This bug affected

cookies with certain kinds of data.  The result was invalid data being sent
back to the web browser.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403319

dlib/server/server_http_1.h

@@ -102,7 +102,7 @@ namespace dlib
 
         unsigned char to_hex( unsigned char x ) const 
         {
-            return x + (x > 9 ? 'A' : '0');
+            return x + (x > 9 ? ('A'-10) : '0');
         }
 
         const std::string urlencode( const std::string& s ) const