Switch to HTML5 history API

[julen]

The editor and part of the reports' client-side code are using an old, jQuery-based, hashchange-event-based router which has been doing its job — however HTML5 wasn't a thing implemented in browsers back when this router was introduced, this being the only approach to client-side routing.

At the moment we are seeing the limits of it though. For instance, sometimes the state of the app cannot be kept in sync with the URL without appending a new browser history entry.

As of today pushState()/replaceState() along with the onpopstate event are well-supported in browsers and it is the way to go, so we should eventually switch to using it instead.