added the core field to the packages, any core package can not be deleted.
In future we can add more to the default list initially, for now we just need 1
final changes and fixes to core fields. Devs should re-install as this is a DB change. Upgrade logic supplied for @ja
fixed upgrade to include helper on p-t-a model
removed shipping_library from admin/shop/shipping, and more maintenance on subsystem files
added create function, hotfix
prod_types can now be deleted (conditional) and fixed an error on upgrade where constructor could not be called
fixed sort of countries by name, fixed shippping form options
fixed urk plugin on express checkout view
-replaced shipping_library with shipping2_library
-replaced shop_clas and nitrocart_core libraries with single class
-updated gitignor,
-removed Enums file