Item descriptions and more compact match history

[DrInfiniteExplorer]

Made rendering of match history more horizontally compact, as on some screens the table stretches very wide. Also added item description popups in match history.

Removed the min-width property from #summonerGamesContainer to make it possible to render the table on smaller screens without horizontal scrolling. Added class for identifying table headers for headers in the summonerGames-table in the match-history. Added css to make sure that the 'items' and 'date' collumns do not introduce awkward linebreaks. Reduced padding on '#summonerGames th' and '#summonerGames td'.

Turned the item-'s into

...

to enable item-descriptions on the match-history page. Added css-rules for 'table.statistics ul.itemDesc', 'table.statistics .item' and 'table.statistics item:hover .itemDesc' to handle the actual popups. Added margin-bottom to #summonerGames to prevent page from re-layouting when displaying vertically long item descriptions (result from the page becomming less wide with introduction of horizontal scroll bar).