Improve history/back button behavion for preview
Improve history/back button behavion for preview

Now opening a preview link directly will replace the current history
entry with the hash-less url and then push the url containing the hash.
That way using the back button will always work, and you don't risk
going back to some other page you wouldn't expect.

mic4ael/indico,DirkHoffmann/indico,pferreir/indico,mvidalgarcia/indico,indico/indico,indico/indico,mvidalgarcia/indico,pferreir/indico,mvidalgarcia/indico,DirkHoffmann/indico,mic4ael/indico,pferreir/indico,OmeGak/indico,mvidalgarcia/indico,ThiefMaster/indico,ThiefMaster/indico,indico/indico,OmeGak/indico,ThiefMaster/indico,OmeGak/indico,mic4ael/indico,DirkHoffmann/indico,ThiefMaster/indico,indico/indico,OmeGak/indico,mic4ael/indico,pferreir/indico,DirkHoffmann/indico