Re-styled collapsible and collapsible set so the content of the collapsible now is applied the ui-btn-up-%%theme%% class. This way the border will match the border of the header button. In the meantime in the ui-collapsible-content class we remove the background image and tweak the margin/padding to make everything look good.
Combined the expand/collapse handlers into a single one and made extensive use of .toggleClass()
Edited the PHP combiner and .htaccess logic to accommodate this change, as well as allowing manifest files to use a "../" when referencing files, which will be handy when adding themes that don't include structural files yet.
Modified all HTML files to point to /themes/default for their theme.
