* ZF2 #6719: Zend\Db\Sql\Select::order(): accept ExpressionInterface
instead of Expression
* Add unit test for ordering using ExpressionInterface
* Improve existing unit test for ordering using Expression - the
original test actually tested expression functionality, not order
functionality
Remove unnecessary "use" statement
Finally remove old "expression" unit test
Respect aliased tables on cloning the gateway
Revert "Respect aliased tables on cloning the gateway"

This reverts commit 0d77c297c3b79b0909669f41f5595997419b7d28.
Select::quantifier() now accepts ExpressionInterface (thx to @turris)
Merge branch 'feature/#6722-db-order-accepts-expressioninterface'

Close #6722