Handling pushState (&c)

[stuartpb]

/:owner/:repo/issues/new is usually navigated to via pushState, which doesn't get picked up by TamperMonkey (because how could it?). This script should be rewritten to match all URLs on GitHub (assuming such a navigation could start from anywhere), and to somehow detect when a pushState-type event happens. (There doesn't seem to be a canonical event for this, so it'll have to be a bit of a pickle.)