Automatically name placed snitches

[awoo-civ]

The name should just be the same as the name of the previously-placed snitch.

I've been privately using this functionality for years now and it has proven to be more accurate than one would expect from such a simple heuristic.

The implementation must yield to the recently-added auto rename functionality: #31.

[Gjum]

Good idea, and much more straightforward both to understand and implement than any location/distance based naming schemes.