PHP Notice in marketplace component.

Fixes #561.
Merge pull request #562 from garyc40/pr-561

PHP Notice in marketplace component.
Merge pull request #559 from MPolleke/master

More NL updates
Integrate visitor meta with customer data API.

Fixes #566.
Use method rather than accessing property directly
Fix whitespace and add brackets
Fix add to cart bug.

Fixes #514.
No need to return after wp_die(), as wp_die() dies.  How many dies would a wp_die() die if a wp_die() could die() die()?
Modifications to marketplace component.
Hook wpsc_ajax literal to wp-e-commerce script instead of wp-e-commerce-dynamic - as I'd like to look into deprecating that.
Have wpsc_create_or_update_tables() return an array of failures, rather than false.  Changing the return output actually has no effect on core usage, it simply makes debugging utilizing this function far more useful.
Tin foil hardening.
Merge pull request #572 from leewillis77/more_ship_api_fixes

Another shipping api fix
Remove erroneous widget instantiation.
Merge branch 'master' of github.com:wp-e-commerce/WP-e-Commerce
Fix syntax error in hardening.  Props jjeaton.
More shipping API adherence
Add actions to allow additional info to be output on the order header on acking slips
update german language strings
more localization updates