Basic order factory class
get_order wrapper function for new factory
Replace new WC_Order calls with get_order
Created WC_Abstract_Order, extended by WC_Order
Restore get_order call in WC_Order constructor
WC_Order is default class for order factory
Added comment to indicate that WC_Order shouldn't be directly instantiated
Merge remote-tracking branch 'upstream/master' into order-factory-refactor

Conflicts:
	includes/class-wc-order.php
Merge pull request #5678 from coenjacobs/order-factory-refactor

Order factory refactor implementation (take two)