Notice fix Closes #3859.
bump_request_timeout closes #3857
Init no longer needed - settings API refreshes settings Closes #3858
wp_list_pluck #3852
Coupon usage limits per user (using email + ID). Closes #3314
Merge remote-tracking branch 'woo/master'

Conflicts:
	includes/admin/settings/class-wc-settings-shipping.php