NV: NV 518 was deleted in 2018

[cl94]

As it says in the title. NV 518 was deleted as part of the 2010s mass downloading in Carson City, with approval given in November 2018. 2022 GSV shows all signs removed.

[oscar]

Don't know how I missed this, when I overhauled TM routes in the Carson City area (including deleting one confirmed to be decommissioned) after a field check last year.

This doesn't quite affect the current NMP hunt, since NV 518's US50/US395 point (which is now on US395BusCar, with both the US 50 and US 395 mainlines relocated  to the new I-580) and the other JacWay point are too far away from any other point to count as a "near-miss". Still, out of synch with any other TM routes.

I'll take care of this later, when I'm less busy.

[oscar]

Pending pull requests:

https://github.com/TravelMapping/HighwayData/pull/5820
https://github.com/TravelMapping/HighwayData/pull/5821 (Updates table entry)