Include R kernel for jupyter using IRkernel

[podpearson]

I have recently used R kernel for Jupyter (https://github.com/IRkernel/IRkernel) which was straightforward to install and allows you to run R in jupyter notebooks just like you would use python. I intend to create a PR when I next need to use R. In the meantime, please shout if you have strong objections to this.

One thing I did realise when doing this is that R packages should be installed using conda, rather than R's own install.packages or other methods. See https://docs.anaconda.com/anaconda/packages/r-language-pkg-docs/. E.g. to install ape use conda install -c r r-ape.

[alimanfoo]

Thanks @podpearson, no objections to a PR adding the necessary conda packages.

[alimanfoo]

Btw binder is currently configured to install from the conda-forge channel, but I don't know which channel is currently best to get R packages from. We might need a bit of care to ensure all R packages come from the correct channel, and packages are not getting pulled from a mix of different channels, which I know has caused problems in the past.

[leehart]

Hi @podpearson . Just looking through old issues and wondering if this is still relevant? Or we can close as "not planned".