Added support for preloading javascript libs ($template->preload_js()). Updated admin theme and Tigra Tree Menu to support this + JS_{HEADER,FOOTER} variables.
# Used for testing mod_rewrite.
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule (.*) install.php?do=modrewrite_test&str=$1
</IfModule>