First pass at conditionally loading theme engines.

Theme Engine 2.0 defaults off.  To test it and turn it on, simply add_filter( '_wpsc_maybe_activate_theme_engine_v2', '__return_true' );
Next pass.  Same rules apply as before, defaults off, filter it on.
Don't crash on recalculation of quotes when not methods
Use existing recalculation routines rather than replicate the same code a third, or fifth time in the same class.
Check method and option parameter set before using them
Add a filter to adjust class names added to class related attributes
Useful for places that display category lists
When there is an error, but there are also quotes, don't stop
Return the error and the quotes
Check for country having regions before validating regions
Avoids clearing invalid region if regions are not defined for a country
Don't blank billing/shipping region on country update without shipping region specified
Merge pull request #1346 from JeffPyeBrook/pr-1331-checkout-field-order-rebased

Check for country having regions before validating regions
Merge pull request #1333 from JeffPyeBrook/pr-1332-dont-crash-on-recalc-with-no-methods-merged

Don't crash on recalculation of quotes when not methods
Merge pull request #1343 from JeffPyeBrook/pr-1341-usps-stop-on-error-with-quotes-rebased

When there is an error, but there are also quotes, don't stop
Resolve more issues with USPS module.
Better error handling for USPS.
Ensure CSS settings can be saved.
Improve check for index.php-ness in the cart URL.  Was causing Add to Cart to fail.
Standardize on WP eCommerce
Remove placeholder image.  At this point (TinyMCE 4.0), this is actually causing more damage than it protects against.
First pass at fixing #1327
Coding standards for /classes folder of new theme engine.
First pass at coding standards cleanup (and a few bug fixes) in /helpers folder for theme engine.
Coding Standards pass at all but template-parts folder.