Bit of maintenance.

* All extension methods are back in one file, this time safeguarded from breaking jQuery by checking if they already exist.
* App.js has been created to hold extension-wide constants. NOTE: App.js does not exist by default, it is auto generated by the compile script.
* Fixing up some invalid HTML attributes and adding media attributes to stylesheet links. All HTML should now validate as HTML5.
* jQuery and all jQuery plugins have been swapped out for their non-minified version to aid in debugging.