DNN Support for dilated convolutions

Hello all! First I want to send my gratitude to all the people working on this great library. It is one of my favourite ML/image processing libraries out there. I specially like the DNN part of it it is so much easier to use then some of the others out there and that you can drive it directly in C++ is great! However I did notice there are some holes in functionality and I was wonder in particular if there is any future plan to add dilated convolutions option to the current DNN convolution layer. I hacked in some support myself to see if they do make a difference so I changed the dnn_segmentation example to add them. Unfortunately my hack would require all examples to be rewritten as there are now two additional parameters in the con layer.

Here are some example images using a trained head segmentation dataset testing it on some celebA images with and without dilation and you can see some decent improvements by just using dilation (that's the only change I didn't touch the network structure itself so far)

Non dilated example 1 Dilated example 1 Non dilated example2 Dilated example 2 Non dilated example3 Dilated example 3 Non dilated example4 Dilated example 4