Revert "Order by in over() takes node."

This reverts commit f7b8cf817ed160d9841ff682f81aa1b9f5ad55ad.
Revert "Partition by takes a single value."

This reverts commit 5eee69dd0c0ff8faa3cd98d8d21f4f8aa6cf4dd1.
Allow multiple parameters in order / partition.