geom/aabb: add a cast call

geom/aabb.hpp

@@ -34,6 +34,21 @@ namespace cruft::geom {
         }
 
 
+        ///////////////////////////////////////////////////////////////////////
+        /// Returns a copy of the AABB with all elements implicitly cast to the
+        /// type `DestinationT`.
+        template <typename DestinationT>
+        constexpr aabb<S, DestinationT>
+        cast (void) const
+        {
+            return {
+                lo.template cast<DestinationT> (),
+                hi.template cast<DestinationT> ()
+            };
+        }
+
+
+
         ///////////////////////////////////////////////////////////////////////
         extent<S,T>
         magnitude (void) const