Adding 'Valid' and 'Same' padding option in Transposed Convolution layer.

src/mlpack/methods/ann/layer/transposed_convolution_impl.hpp

@@ -455,6 +455,7 @@ void TransposedConvolution<
 
   padWidth = (kernelWidth-strideWidth)/2 + kernelWidth-strideWidth%2==1;
   padHeight = (kernelHeight-strideHeight)/2 + kernelHeight-strideHeight%2==1;
+  // If Padding is negative set it to 0.
   if(padWidth<0){
     padWidth = 0;
   }