Made dlib::array usable in C++11 range based for loops by adding

begin() and end() methods.

dlib/array/array_kernel.h

@@ -177,6 +177,13 @@ namespace dlib
             T& item
         );
 
+        typedef T* iterator;
+        typedef const T* const_iterator;
+        iterator                begin()                         { return array_elements; }
+        const_iterator          begin() const                   { return array_elements; }
+        iterator                end()                           { return array_elements+array_size; }
+        const_iterator          end() const                     { return array_elements+array_size; }
+
     private:
 
         typename mem_manager::template rebind<T>::other pool;

dlib/array/array_kernel_abstract.h

@@ -254,6 +254,40 @@ namespace dlib
                        If an exception is thrown then it has no effect on *this.
             !*/
 
+            typedef T* iterator;
+            typedef const T* const_iterator;
+
+            iterator begin(
+            );
+            /*!
+                ensures
+                    - returns an iterator that points to the first element in this array or
+                      end() if the array is empty.
+            !*/
+
+            const_iterator begin(
+            ) const;
+            /*!
+                ensures
+                    - returns a const iterator that points to the first element in this
+                      array or end() if the array is empty.
+            !*/
+
+            iterator end(
+            );
+            /*!
+                ensures
+                    - returns an iterator that points to one past the end of the array.
+            !*/
+
+            const_iterator end(
+            ) const;
+            /*!
+                ensures
+                    - returns a const iterator that points to one past the end of the
+                      array.
+            !*/
+
         private:
 
             // restricted functions