A couple maneuver node features

[KevinW42]

In light of the recent announcement of the improvements being made to maneuver nodes, I thought I'd pitch a couple other ideas I'd been thinking about.

First, the ability to rotate a node without changing its total dV. This could be useful if you're performing a maneuver using all the remaining dV of a stage, like if you're trying to reach a target periapsis for reentry while also reducing your velocity as much as possible. Could also be useful for SRB-only challenges.

Second, the option to have the maneuver node handles orient to the post-burn orbit rather than your current orbit. This would allow easy planning of plane-change maneuvers that don't change your Ap or Pe using only the normal handles instead of having to fiddle with both normal and retrograde.