Adjusted upgrade page links and products

Adjusted links and products. Removed unavailable ones and changed links
Add constant to control deprecated js loading
* constant is off by default

*Also...*
* Wrapped WPeC version constants in if blocks.  This will let developers put something into their wp-config.php file that bumps version numbers automatically to force script reloads, or perhaps for other reasons  My preferred insert is appending the time stamp of the wp-e-commerce.js file to the version stamp.
Merge pull request #1168 from misulicus/patch-18

Adjusted upgrade page links and products
Merge pull request #1170 from JeffPyeBrook/pr-issue-1125-deprecated-js-load

Add constant to control deprecated js loading
Only return once in WPSC_Product::_get()
Merge branch 'master' of github.com:wp-e-commerce/WP-e-Commerce
Have Quantity field default to being shown, rather than hidden, by default on new installs.
Better, though not yet perfected, i18n for live previews.  Also, resolves some NaN errors with live previews attempting to show shipping dimensions when variations are enabled.
Fix currency code UI, fixes #1159
Use billing address by default for PayPal Standard, rather than shipping address.
Ensure that coupon amounts are refreshed when new items are added after a coupon has been applied.  This is a commonly expected UX.  If not desired, it is a simple remove_action() call to unhook this functionality.  Also, some weird spacing standards were in place and resolved, and we've added the user ID as a parameter to the _wpsc_merge_cart action.
Shore up currency and amount validation in PayPal Standard.
Don't show unused form values for PayPal Standard on new installs or installs that have not utilized them.  Not sure why they ever existed here, but they haven't been used in some time.
Don't mangle data types for 0 variable.
Don't fall through on subscriptions.
Checkout form handling of countries, countries regions and states
* The region drop down, when shown will appear in the state/province row rather than below the country.  This means that the relative order of field entry will not change dependant on whether or not a country has regions.
* If billing or shipping country is not being displayed, and current base country has regions, user can now select a region
* If billing or shipping country is not being displayed, and current base country has regions, a region HTML drop down select element is presented rather than a HTML edit control
* If current shipping country does not have regions a region edit HTML element will be displayed in the shipping calculator
* Label for the billing and shipping state rows will change depending on which billing or shipping country is selected. The value of the label will be whatever is defined in the country meta.  For example "State" for USA, "Province" for Canada, etc.
* Checkout form class enhanced to allow all form elements to be returned on request, rather than just active form elements
* Fix issue where shipping state does not change when shipping calculator drop down changes
* Changed misleading information message about ordering availability to be more shipping address oriented
* Put current customer meta values into hidden fields on checkout page just in case store owner hides fields on checkout forms.  This allows any JavaScript actions that have depend on the availability of specific meta items to work properly if the store administrator hides any of the fields in the checkout forms.
* Shipping state/region elements visibility was being changed when billing country was being changed.  Change billing state/region visibility when shipping country changes instead.
* Upper case first letter of region label in country meta
* Add class method to find specific checkout item by matching id or unique name
* Adjusted spacing and tabs to coding standards in some places
* The check for if shipping quotes need to be recalculated is more robust and if the postal code changes, includes a check of all installed shipping modules and if they require the zip code

*Addresses problems described in issue #1119 and should be merged after the PR #1158 which addresses issue #1144*
Merge pull request #1158 from JeffPyeBrook/pr-issue-1144-checkout-page-issues-fixes

Checkout page user interface issues
removed dead code
not necessary to initialize 'label_element' to 'undefined'.
use === to compare with 0.
added missing ;
use !== to compare with undefined.
added global declaration of $wpsc_shipping_modules