Made rectangle implicitly convertible to a chip_details.

dlib/image_transforms/interpolation.h

@@ -1500,6 +1500,7 @@ namespace dlib
     struct chip_details
     {
         chip_details() : angle(0), rows(0), cols(0) {}
+        chip_details(const rectangle& rect_) : rect(rect_),angle(0), rows(rect_.height()), cols(rect_.width()) {}
         chip_details(const drectangle& rect_) : rect(rect_),angle(0), rows(rect_.height()), cols(rect_.width()) {}
         chip_details(const drectangle& rect_, unsigned long size) : rect(rect_),angle(0) 
         { compute_dims_from_size(size); }

dlib/image_transforms/interpolation_abstract.h

@@ -934,6 +934,18 @@ namespace dlib
                 - #cols == rect_.width()
         !*/
 
+        chip_details(
+            const rectangle& rect_
+        );
+        /*!
+            ensures
+                - #rect == rect_
+                - #size() == rect_.area()
+                - #angle == 0
+                - #rows == rect_.height()
+                - #cols == rect_.width()
+        !*/
+
         chip_details(
             const drectangle& rect_, 
             unsigned long size_