closes#394
- closes potential phishing avenues by preventing external sites from changing the blogs url in the background after opening
- see https://mathiasbynens.github.io/rel-noopener/ for more info
closes#321, closes#323
- use `requestAnimationFrame` and related techniques to minimise scroll processing
- add an `isLoading` guard to ensure we don't try to process anything until the next page has been loaded+inserted
- check for a 404 as an indication we've loaded as many pages as possible at which point the scroll behaviour is removed
- sanitize `window.location.pathname` to remove hash params and any double-slashes that may result
- add a 100px buffer from the bottom of the screen so that it's not necessary to exactly hit the bottom before infinite loading is triggered
Kevin Ansfield