Remember last user's page

[nbeloglazov]

If user comes to main page, like http://nonojure.com/ (without sub pages) redirect him to last visited page. Example:

1. I came first time to the site http://nonojure.com
2. Puzzle browser is shown.
3. I choose puzzle with id aaabbbccc42
4. Puzzle shown with url http://nonojure.com/puzzle/aaabbbccc42
5. Solved half of the puzzle and closed page.
6. Opened page http://nonojure.com
   Here I should be redirected to last visited page http://nonojure.com/puzzle/aaabbbccc42. If user opened not main page but with specific url then no redirect is needed.

Last visited page can be stored in browser local storage, no need to keep it on server I think.