Large refactoring

* Load player data on the fly instead of on ready() because there are too many friends now
* Refactor JS/CSS to use :visible and table classes instead of iterating over the li's
* Use CSS pseudoclasses for avatars instead of <img> to reduce number of elements
* Remove medium avatars because they're too damn big
* Replace theme.grey.css with tablesorter.css and theme.css
* Replace in-line styles
* Move $player_ids definition to file
Merge branch 'deagle' of https://github.com/Southpaw018/steamAchievementCheck into deagle