Define line_subtotal and line_subtotal_tax to avoid PHP notice in cart.
Use global $current_user in my-account/edit address.

Avoid PHP notice for undefined variable.
Use wp_nonce_field. $woocommerce->nonce_field is deprecated.
woocommerce_exclude_order_comments() is now exclude_order_comments()
Rename attributes class to woocommerce_attributes. Fixes #4019

.product_attributes should be .woocommerce_attributes
Merge pull request #4017 from scottbasgaard/master

Define line_subtotal and line_subtotal_tax to avoid PHP notice in cart.