Canonicalize Cross-Sells invokation

[anastis]

WC v2.0.5

The function woocommerce_cross_sell_display() doesn't follow the pattern like woocommerce_output_related_products() and woocommerce_upsell_display().

While their three respective files are quite similar in nature, the later two provide a way to pass posts_per_page and colums parameters. woocommerce_cross_sell_display() does not, so themes have to override the file /cart/cross-sells.php in order to change them.

[coenjacobs]

I've put this on the roadmap for 2.1 to look at.