Dashboard Widgets for 1.6 Admin Home Page (including ajax infrastructure)

Fix test for ajax in init_languages
CHANGE-430 - stats_customers_referrals.php does not allow popup on Discount Coupon
CHANGE-431 - Fix error with tax default for not-logged-in shoppers
CHANGE-432 - PHP 5.4 causing warnings in debug logs
CHANGE-434 - Add additional SSL detection checks to accommodate yet another poorly configured SSL proxy used by various hosting companies
Administrative - fixing formatting (spaces/tabs cleanup) and removing duplication in COWOA code
CHANGE-435 - Set reply-to header in admin copy of order-confirmation email - to make for easier replying to customers
CHANGE-436 - Update admin configure.php defines for when Admin is in SSL: the language icons were being accessed as non-secure resources.
CHANGE-367 - Dashboard Widgets for 1.6 Admin Home Page - set missing header content
CHANGE-437 - Set proper exclusion metatags to prevent gv_faq pages from being spidered/indexed
CHANGE-442 - HTML id=reviewsContent already defined error in reviews sidebox
CHANGE-445 - Overrides: add "classic" folder to \includes\index_filters\ to match pattern of indicating which folders support overrides
CHANGE-444 - Missing 'echo' and centerboxes in tpl_product_info_noproduct.php
CHANGE-446 - Cleanup: Remove duplicate code in update_product.php
CHANGE-367 - Dashboard Widgets for 1.6 Admin Home Page (including ajax infrastructure)
(added error checking, so that other ajax scripts don't trigger language-file-not-found errors caused by the last commit to this file)
CHANGE-452 - Add multiple-choice support for the Store Pickup shipping module
CHANGE-451 - Add canonical link handling to kick in properly in the occasional case where site operates entirely in SSL
CHANGE-453 - Shorten some payment module language strings for better fit on smaller screens
(partial) CHANGE-407 - Incorporate schema.org microdata markup for product_info pages
CHANGE-449 - Add hooks to order class to allow for customized handling of taxes