Fix for issue #20

Added a little question mark symbol (taken from [Wikipedia Commons](http://commons.wikimedia.org/wiki/File:Circle_question_mark.png) which allows us to do what we want with it) next to all options that had a corresponding feature page on enhancedsteam.com. All links open in a new window.

Also changed the changelog to readonly as users wouldn't need to be able to edit it within the settings page.