Database Upgrade Routine to rename old _wpsc_* product metadata array keys so they no longer include the '_wpsc_' prefix

Fixes #492
Changelog for database upgrade routine
Remove debugging statement
Use strict comparison and fix whitespace issues

As per feedback from @JustinSainton.
Should now match http://make.wordpress.org/core/handbook/coding-standards/php/.
Filter $json_response object

Used quite nicely in conjunction with the new custom trigger.
Update Dutch translation
Don't use wp_convert_bytes_to_hr() deprecated function. Fixes #508.

As per http://core.trac.wordpress.org/ticket/19067, WordPress 3.6 deprecates the wp_convert_bytes_to_hr() function in favour of the size_format() (which was was added in WordPress 2.3).
Add custom JS event for when cart is emptied

Necessary if you've, for example, hooked into the fancy notification event to update cart totals somewhere, and need to do the same when emptying the cart.
Fix warning in coupons admin if no order query in URL.
Show cost before shipping row above coupon code field.
Use methods instead of accessing properties directly
Turns out disabling mandatory boxes, while checked, causes them to not be submitted.  This is a problem.

Readonly gives the same effect, but POSTs them properly.
Fix typo in variable function, also, totally fix disabled/readonly issue.

Missed a spot.
Add shipping.php and rss.php helpers
Bump stable tag
Updated readme.md
Add 'wpsc_save_product_order' action and use it to save category product order in the term_relationships table.
Back-end product ordering for categories.
Front-end product ordering in categories (theme engine v1).
Fix removing filter for drag 'n' drop ordering in admin.