Fixed a bug in randomize_samples(). It forced each element of the input arrays

to move to a new position but was random amongst all permutations with such
moves.  However, this isn't really fully random so this function has been fixed
so it does exactly what the spec says it should.

dlib/svm/svm.h

@@ -954,11 +954,8 @@ namespace dlib
         long n = t.size()-1;
         while (n > 0)
         {
-            // put a random integer into idx
-            unsigned long idx = r.get_random_32bit_number();
-
-            // make idx be less than n
-            idx %= n;
+            // pick a random index to swap into t[n]
+            const unsigned long idx = r.get_random_32bit_number()%(n+1);
 
             // swap our randomly selected index into the n position
             exchange(t(idx), t(n));
@@ -996,11 +993,8 @@ namespace dlib
         long n = t.size()-1;
         while (n > 0)
         {
-            // put a random integer into idx
-            unsigned long idx = r.get_random_32bit_number();
-
-            // make idx be less than n
-            idx %= n;
+            // pick a random index to swap into t[n]
+            const unsigned long idx = r.get_random_32bit_number()%(n+1);
 
             // swap our randomly selected index into the n position
             exchange(t[idx], t[n]);
@@ -1055,11 +1049,8 @@ namespace dlib
         long n = t.size()-1;
         while (n > 0)
         {
-            // put a random integer into idx
-            unsigned long idx = r.get_random_32bit_number();
-
-            // make idx be less than n
-            idx %= n;
+            // pick a random index to swap into t[n]
+            const unsigned long idx = r.get_random_32bit_number()%(n+1);
 
             // swap our randomly selected index into the n position
             exchange(t(idx), t(n));
@@ -1093,11 +1084,8 @@ namespace dlib
         long n = t.size()-1;
         while (n > 0)
         {
-            // put a random integer into idx
-            unsigned long idx = r.get_random_32bit_number();
-
-            // make idx be less than n
-            idx %= n;
+            // pick a random index to swap into t[n]
+            const unsigned long idx = r.get_random_32bit_number()%(n+1);
 
             // swap our randomly selected index into the n position
             exchange(t[idx], t[n]);
@@ -1144,11 +1132,8 @@ namespace dlib
         long n = t.size()-1;
         while (n > 0)
         {
-            // put a random integer into idx
-            unsigned long idx = r.get_random_32bit_number();
-
-            // make idx be less than n
-            idx %= n;
+            // pick a random index to swap into t[n]
+            const unsigned long idx = r.get_random_32bit_number()%(n+1);
 
             // swap our randomly selected index into the n position
             exchange(t(idx), t(n));
@@ -1171,11 +1156,8 @@ namespace dlib
         long n = t.size()-1;
         while (n > 0)
         {
-            // put a random integer into idx
-            unsigned long idx = r.get_random_32bit_number();
-
-            // make idx be less than n
-            idx %= n;
+            // pick a random index to swap into t[n]
+            const unsigned long idx = r.get_random_32bit_number()%(n+1);
 
             // swap our randomly selected index into the n position
             exchange(t[idx], t[n]);