Scenario: a rail system that has iron track with track kits applied in various places (e.g. locking tracks) is to be upgraded to electric track. At the moment the iron tracks with the kits are only recognised by the track relayer if a full rail with the track kit applied is used as the template (i.e. kind of how it used to work).

It would be great if it just replaced the underlying track, leaving the track kits, and their underlying state. This is important because in a signalled system, the locking tracks etc will be changing state as the train goes over them (think about train lockdown mode, for instance - the train might not be fully past when the track relayer cart goes over the locking track, but it needs to stay "unlocked" for the whole train, other wise it will lock in place, probably across two signals blocks...)

Note to self, check status of this.

Related to #1197