Commented code

Added comments in enhancedsteam.js for highlighting items on friend's
wishlists, hiding owned games from the main store page, hiding DLC for
unowned games, calculating the total cost of all the games on a user's
wishlist, and removing all pre-owned items from a wishlist.
More comments

Added more comments into code
Added many more comments

Made changes to comments for clarity/consistency, and added comments for
more uncommented sections of code.
Merge pull request #442 from Stevoisiak/dev

Added comments to sections of uncommented code