filter to override theme files without hooking into transients
Updated Paypal accepted currencies

According to https://developer.paypal.com/webapps/developer/docs/classic/api/currency_codes/#paypal
whitespace after !
Visitor Profile and Meta API implementation that does not use WordPress Users
No user records, no user meta, fully backwards compatible.

Also includes:
* Staged cleanup of expired visitors, respecting memory and processing time.
* New visitors expire quickly, longer term visitors expire later.
* Profiles are not automatically deleted if profile becomes connected to a wordpress user with posts, comments or purchases,
* AJAX Meta API, get and set current user meta from javascript/jQuery.
* Upgrade routine to move WordPress user based profiles to new infrastructure without loss of cart or other information
* Fix to prevent multiple profile creation when WPEC is using page caching

Status:
* Unit testing done, ready for integration testing ( ps. I hid 5 bugs in the code to be sure you tested it well, see if you can find them! )
* Needs upgrade testing
* Needs Install testing
Initialization includes
fixed typo in mysql column name
manually re-merge from upstream/master
Merge pull request #878 from JeffPyeBrook/pr-visitor-meta

Visitor Profile and Meta API implementation that does not use WordPress Users
confirm that customer cookie is set for admin users logged into web site
Don't double set expiration time on new visitor creation
Merge pull request #879 from JeffPyeBrook/pr-visitor-meta

Confirm that customer cookie is set for admin users logged into web site
Don't set cookie in HTTP only mode, our javascript will not be able to see the customer id
Merge pull request #880 from JeffPyeBrook/pr-visitor-meta

Customer/ Visitor Meta Bug changes/fixes
Removing border for form-field
Improving the tags taxonomy

Adding a chose_from_most_used label and fixing some wording mistakes
Quick Capitalization fix for tags taxonomy
Merge pull request #882 from NikV/master

Removing border for form-field
update code to current standards
Fix missing $pwdb in delete function
Add WPSC_Visitor class to make it more convenient to access visitors, primarily useful inside of WPEC or admin related plugins