[rekonq] autohide statusbar

[Lionel Chauvin]

I re-use the code of this feature to display link urls in the urlbar instead 
of a statusbar. 

When the user place his mouse over a link,  the link url replace the current 
url in the urlbar after a short time. This url is colored in gray.

I've never seen this in other browsers, but I think it's a good idea. The 
statubar is then not needed.

I will propose this feature for 0.3.