Implements indication of starred questions in question-list

`sx-question-list-favorite` inherits face from
`sx-question-list-score-upvoted`

Favorite is displayed using char \x2b26 WHITE MEDIUM DIAMOND.
Merge pull request #72 from jleechpe/sx-questions-show-favorite

Implements indication of starred questions in question-list
QUICK-FIX: Link regexp Fixes #74