Settings API should use h3 rather than h4 when outputting titles
[2.2] Product attribute shortcode should return columns class

Fixes #6481
Bump master version to 2.3-bleeding
[2.2] Prevent address fields being empty when editing an address within an order

Fixes #6476
[2.2] Added woocommerce_product_subcategories_hide_empty filter

Use add_filter( ‘woocommerce_product_subcategories_hide_empty’,
‘__return_true’ ); to enable. Fixes #6482
[2.2] Prevent bulk edit from breaking sale price scheduled dates

Fixes #6474
Removed save_post remove_action call which breaks 3rd party plugins.

Fixes #6485, but means #6376 needs another solution.