Keep non-hash URL in history

[qsantos]

Navigating comments adds a hash to the URL. Using the back button does not help in removing it.

Things to take into consideration:

• if the page was initially loaded with a hash, it should be kept (what about hash charges)
• it should still be possible to access the URL pointing to the current comment; in particular, coding the browser and reopening it should navigate back to the comment where the user was at