Feature request: implement make_subplots functionality

[AndreiDegtiarev]

In comparison to python version of plotly library, the subplots functionality I'm mostly missing in Xplot. Target behavior see https://plot.ly/python/subplots/
See also discussion fsprojects/IfSharp#186
I believe, that this feature is the enabler for many machine learning helper algorithms that are already implemented in the python libraries (like Pandas or Seaborn) which make life of data engineers much easier.

[cartermp]

Closing as duplicate of #54