Fixes ES5 and non-standard pages in IE 8

The ES5 and non-standard pages should now work in IE 8 again.
(The ES6 page, puzzlingly, seems to make it freeze or crash. Oh well, maybe later.)

Fixes include:
 * Fallback for hsl() colours. (I prefer the hsl format for clarity of reading and understanding - the relation between the "hover" and normal colours is made obvious in HSL, so I opt to leave both colour formats in the CSS.)
 * "Show obsolete browsers" checkbox works again
 * Fallback for opacity when selecting a column
 * Tooltips work again (incorrectly uses String#trim and Array#forEach)