* Updated plugin settings UI. Completely overhauled admin header and navigation. Made additional improvements to various elements (icons, buttons, toggles, etc.).
* Added additional checks to allow PERFMATTERS_CACHE_DIR and PERFMATTERS_CACHE_URL to be manually set in wp-config.php.
* Updated user agent for local font remote request.
* Fixed an issue where multiple preload tags for the same resource could be printed if the resource was matched more than once in the DOM.
* Fixed an issue where an individually delayed script would fail to load if it matched more than one delayed script entry.
* Fixed an issue where FastClick script could still load even if Delay JS was turned off.
* Translation updates.
