Rectify: remember last map view

[jidanni]

When we push "rectify" by default we start at a whole world view.
Perhaps simply remember where the user was recently looking last time he used it
on a previous map, and start there instead.
Sort of like on OSM.org, if I was looking at Alabama last time I used the site,
a year later in the same browser, that's where I'll be looking initially again,
logged in or not.