Tweaks to previously added problem statement options and 3 new ones.

A couple of things to the statement template.
* An option to add a favicon (The icons that appear in browser tabs), by default it uses the one for topcoder.com, which I am not sure is a good thing because my mind tends to mix it up with TC forum pages. But it can be changed or disabled.
* An option to make statement use a completely custom external style sheet. Allowing users to customize the theme entirely without modifying the HTML template.
* An option to add an -> before the expected return value. I just like it :)
* All options, except the grid one and favicon, now just modify the style sheet and leave the statement HTML untouched.
* Remove a "hj" in the low contrast style. Not sure how it got there.