MXNet pad is described at:
https://mxnet.incubator.apache.org/api/python/symbol/symbol.html#mxnet.symbol.pad

Add support for parameter 'None' in MXNet slice operator.

MXNet 'slice' is described at
https://mxnet.incubator.apache.org/api/python/symbol/symbol.html#mxnet.symbol.slice

Add support for MXNet cos, sin, arctan

MXNet 'cos' is described at
https://mxnet.incubator.apache.org/api/python/symbol/symbol.html#mxnet.symbol.cos

MXNet 'sin' is described at
https://mxnet.incubator.apache.org/api/python/symbol/symbol.html#mxnet.symbol.sin

MXNet arctan is descirbed at
https://mxnet.incubator.apache.org/api/python/symbol/symbol.html#mxnet.symbol.arctan

Add support for MXNet 1D Convolution and 1D Deconvolution

MXNet convolution is described at:
https://mxnet.incubator.apache.org/api/python/symbol/symbol.html#mxnet.symbol.Convolution

MXNet Deconvolution is described at:
https://mxnet.incubator.apache.org/api/python/symbol/symbol.html#mxnet.symbol.Deconvolution