Add RISE-lab plugin for jupyterlab_rise

[f0k]

This adds a plugin for jupyterlab_rise. The current RISE plugin is not compatible with it. It is not very smart, instead of trying to access the underlying reveal.js, it steps through the slides and observes whether the slide anchor in the window URL was updated, otherwise it assumes we reached the end.

It requires jupyter to be invoked with jupyter lab (not jupyter notebook), and then to be passed an URL of the form:
http://server:port/rise/your_path/your_notebook.ipynb?token=your_token

Works for me, maybe it will be useful for others!

closes #325

[astefanutti]

Thanks for your contribution! I've left a comment about the plugin activation logic. Other than that it looks good to me.

[astefanutti]

This can break other plugins activation. Would there be a more robust way to detect it's called in a jupyterlab_rise context?

Alternatively, we could exclude the plugin here:

decktape/decktape.js

Line 350 in 6735cec

if (id === 'generic') continue;

but I'd rather go with the former approach.

[f0k]

Ah, good point. So this would break automatic plugin selection. I'll check if there is a way to tell whether we are in the correct context without waiting for the presentation to be loaded, but it will take a while until I'll get around to that. If I don't find anything, would it be permissible to do a waitForSelector and only return after a not-too-long timeout?

[f0k]

Ok, I've added a very basic jupyterlab_rise detection: It checks whether the window title is "Rise". This is the only part that remains from the original web page as delivered by the server, everything else in the DOM seems to be replaced via javascript after loading the page, and would be unreliable to test for. It will break plugin detection if someone deliberately titled their reveal.js (or other) presentation "Rise", but I guess we could live with that?