Refactor Backend and Layer interfaces

include/layers/activation.hpp

@@ -2,6 +2,7 @@
 
 #include "backend/tensor.hpp"
 #include "backend/backend.hpp"
+#include "layers/layer.hpp"
 
 namespace CUDANet::Layers {
 
@@ -19,7 +20,7 @@ enum ActivationType { SIGMOID, RELU, SOFTMAX, NONE };
  * @brief Utility class that performs activation
  * 
  */
-class Activation {
+class Activation : Layer {
   public:
 
     Activation() = default;