Catchment area display

[uzurpator]

Well.

I suggest, as this forum says, to make the 'catchment area' display of a station display catchment of all stations on the screen (ie including these which are already built).

This would make building of new stations much easier in large cities as we could control how much of the city is covered in our stations.

[m3henry]

but make the existing ones:
notpurple/lightpurple/lightblue/semitransparentthing/purplecorersonly?
and the ones to be added, as they currently are