Preserve the history of destroyed vessels for future viewing

[eggrobin]

Scripsit @lpgagnon:

After about a year, the moon ate my first moon orbiter while I wasn't looking. As I try to find an older save from which I can watch the end, I wonder: would it be possible to preserve the history of destroyed vessels for future viewing?

Relatedly, it would be nice to not lose all history upon landing.

Now that we have solved #2400 once and for all—but—Once and for all!, we should be able to do that without ridiculously enlarging saves. We already have zombies, this would be a matter of adding more stuff to them, and coming up with a way to look at that in the case of destroyed vessels.

Principia/ksp_plugin/plugin.hpp

Lines 568 to 574 in 977a315

	// Contains the adaptive step parameters for the vessel that existed in the
	// past but are no longer known to the plugin. Useful to avoid losing the
	// parameters, e.g., when a vessel hits the ground.
	// NOTE(phl): This is a leaky map, in the sense that we don't remove deleted
	// vessels from it. Hopefully it's small enough that we don't care.
	std::map<GUID, Ephemeris<Barycentric>::AdaptiveStepParameters>
	zombie_prediction_adaptive_step_parameters_;

[eggrobin]

(It is amusing to note that looking at such zombie trajectories could require reanimation.)