See #756 UPS/USPS modules try to calculate rates over and over

Here are the modifications indicated in issue #756:

a) Modified the TXT_WPSC_OVER_UPS_WEIGHT constant to
TXT_WPSC_OVER_WEIGHT in wpsc-languages/EN_en.php. The text now reads:
"Your order exceeds the standard shipping weight limit. Please contact
us to quote other shipping alternatives.". This text is now used in
both USPS and UPS weight limit checks.

b) Added a checkbox to provide the ability of disabling international
shipping, for those who don't want to offer it. The standard behavior
is not affected (Enabled). This is part of the getQuote initial
conditions check.

c) The UPS module getQuote filter now matches the more efficient USPS
rates initial conditions check. The data checked is the destination
country, zip code, and shipment weight. Then there's a shipper weight
limit check if you want the whole shipment to be rated as one envelope.
If any of these data checks fail, bail. If these datas checks are ok,
check cache and return the rate table if found. Else, continue the rate
table request process.

d) The UPS cache check process now matches the USPS cache check
process, which uses less variables.

e) Moved UPS's shipment being assigned at the constructor to getQuote
(right after the bail checks). This avoids the shipment being assigned
to the ash_ups class every time this class is instantiated during each
session, matching the USPS module behavior.

f) I removed some redundant variable assignments done at the end of
getQuote (rates_expire, set_destination). These values have already
being assigned before the cache check.

g) I'm assigning the shipper's internal name to the $args (UPS) or
$data (USPS) arrays, so the wpsc_cart_shipment hook $this->name
parameter is now changed to $args or $data, depending on the shipper
module. I'm using this hook to apply a partitioning problem/bin packing
algorithm to reduce the package quantity, and therefore reduce the
shipping cost. It's a new hook, so at this point no one else should be
affected with this modification.

h) I'm adding a new hook called wpsc_shipment_data, after setting the
quote request data and before requesting the quote. I'm using this hook
to check if the shipment could be rated as shipped as an envelope
(movies), instead of packages, to modify on the shipment type data flag.

i) I'm adding another hook called wpsc_rates_table right before
returning the rates table. I use this to add packaging costs to the
rates, based on the shipment contents.

If you have any questions or comments, please don't hesitate to ask.
Revert "See #756 UPS/USPS modules try to calculate rates over and over"

This reverts commit 45e184a127d69b2fba639117dbad68da336aebe0.
PR for issue #756 UPS/USPS modules try to calculate rates over and over with corrected spacing

Same commit, but corrected spacing and removed the EN_en.php file
modification, in favor of __('Your order exceeds the standard shipping
weight limit. Please contact us to quote other shipping
alternatives.','wpsc’).
Revert "PR for issue #756 UPS/USPS modules try to calculate rates over and over with corrected spacing"

This reverts commit de016f0f0901652ff0114ec6779228d17e548d6e.
PR for issue #756 UPS/USPS modules try to calculate rates over and over (missed 2 spacings)

Same commit, but noticed I missed respacing 2 lines.
Usps Weird characters again

Fix for #793
Merge pull request #794 from misulicus/patch-6

Usps Weird characters again
Fix wpsc_meta_migrate() omitting 'wpsc_' prefix.
Bump stable tag and changelog.
Merge pull request #791 from benjaminprojas/feature-purchase-meta

Added Purchase Meta feature
Merge pull request #757 from ReactorShop/master

PR for issue #756 UPS/USPS modules try to calculate rates over and over
Fix anon users on multisite.
Fix: User counts are incorrect when there are thousands separators.

Fixes #798
Fix the hopping Save Product Files button. Fixes #802.
Merge pull request #804 from garyc40/pr-797

Fix anon users on multisite.
Merge pull request #806 from garyc40/pr-802

Fix the hopping Save Product Files button.
Merge pull request #805 from garyc40/pr-798

Fix: User counts are incorrect when there are thousands separators.
Improvements to product currency and quantity discounts layout.
Merge pull request #808 from benhuson/issue_777_pricing

Improvements to product currency and quantity discounts layout.
Remove the logic that replaces product images with site header images. Could not find any case where this would be useful.
In any case, the logic was faulty and caused product images to be removed on single product pagews
when using a WP theme that did not support header images.