Merge pull request #4717 from tivnet/upstream-master

wc-cart-functions : removed unused $woocommerce and fixed phpdocs
file_exists check for wc_get_template
Merge pull request #4719 from tivnet/upstream-master

sort_callback_params() phpdoc fix
taxonomy_is_product_attribute() phpdoc fix
Need to actually check $outdated. Derp. @coenjacobs
Only string param in taxonomy_is_product_attribute
Hide empty categories in the product_categories shortcode Closes #4689
Set $time Closes #4718
twenty thirteen single product layout
Merge remote-tracking branch 'upstream/master' into upstream-master
Merge remote-tracking branch 'upstream/master' into upstream-master
Merge branch 'upstream-master'

Conflicts:
	includes/wc-conditional-functions.php