Use DOM history API for navigating directories

[gnestor]

Closes #307

[gnestor]

This passes my basic user testing but I'm pretty sure there are some edge cases that may break this so it's marked as WIP.

[rgbkrk]

Awesome thanks for going after this!

One edge case worth trying — do a right click and “open in new tab”

[blink1073]

This is great @gnestor! We'll be cribbing this for use with lab/tree. cf jupyterlab/jupyterlab#2532

[blink1073]

cc @afshin

[afshin]

Thanks for the heads up, @blink1073. Nice one, @gnestor!

[takluyver]

Nice, this feels super snappy. :-) I've tried opening in a new tab as @rgbkrk suggests, and it seems to work correctly.

However, something is going wrong with the breadcrumbs - when I click on them to navigate back up, the URL bar does not update. And if I navigate down three directories and then use the breadcrumbs to go up one, it requests the wrong thing (e.g. if I navigate to Code/astcheck/dist, and then click astcheck in the breadcrumbs, it requests astcheck instead of Code/astcheck).

[takluyver]

I pushed a couple of commits to fix things for me and make sure we're using base_url where necessary.

The test failures appear to be unrelated - #3127

[takluyver]

@gnestor is there more you want to do with this, or shall we merge it so that people can try it out in master?

[gnestor]

@takluyver Thanks for fixing the URL construction bits 👍 Let's merge!

[takluyver]

:-) As this is a user-visible change, it would be good to write a little bit about it for the release notes.

[gnestor]

Is this the same test error that you saw before: https://travis-ci.org/jupyter/notebook/builds/316101183?utm_source=email&utm_medium=notification

Ok, I'll update release notes now...

[takluyver]

No, that's a different failure. It seems to be that the linkcheck is failing because nbviewer is down.

[takluyver]

jupyter/nbviewer#746