filterable train station lists

[ahicks92]

Sometimes one wants to find train stations without going insane. Suppose that in addition to #304, we add a second flat view. This view would take over alt+1 to alt+0. or something along those lines. Each of these would be a user configured list of words or Lua string patterns. Each button toggles through all assigned to that button. For example 1 could be resources, 2 could be dropoff/pickup, and 3 could be east/south/north/west. These filters are then all applied at the same time. The other issue establishes a good UI for hierarchical relationships. This establishes a way around that: you can conveniently ask questions like "show all stations to do with iron in the west" or, with the full power of Lua patterns, "show all stations to do with iron, water, or copper in the north and east". Combined with showing status information in the UI, one then gets a reasonably convenient view of the statuses of all train stops in their network. Examples of convenient info include things like contents of all chests within 2 tiles of the track, whether a train is present and what it contains, etc.

To get people started, we can preconfigure some of these, and/or offer presets. For example, all ores, or "anything fluid" or whatever.