Corrected tax charge differences between store checkout page and Google Checkout site.

Addressed "Cannot find the declaration of element 'add-merchant-order-number'"XML error in Google Checkout Merchant Center (Sandbox Integration).

Added an EXTRAS folder containing modifications to help order tracking in ORDERS, INVOICE and PACKING SLIP pages using both store order number and google order number.

Created a Troubleshoot file that contain fixes to issues discussed in the Google Checkout IPN forum to help address issues affecting only specific osc users. This folder will continue to evolve as more fixes/solutions to uncommon problems are found.