refactor: minor changes

refactor: updated readme

refactor: updated readme

new: added mnist example notebook

fix(Tensor): crashes when deallocating uninitialized tensor

new(Storage and Tensor): added `to` method

fix: tensor spec infer in add and mul

fix: multiple fixes

refactor(AddCudaKernel): remove redundant code

new: added cuda kernel for add op

fix(numpy add kernel): wrong dimensionality reduction in gradients

fix(numpy mul kernel): wrong dimensionality reduction in gradients

fix(mul cuda kernel): return updated modes on descriptor initialization

Merge pull request #6 from oKatanaaa/softmaxKernel

Merge branch 'master' into softmaxKernel