Railway halts should be styled like stations

[claysmalley]

I overlooked this when reviewing #790, but railway=halt is a type of station, not a type of stop. In the US, the de facto accepted practice is to use railway=halt for stations with flag-stop service. Other countries use different criteria to distinguish railway=halt from railway=station, but regardless, either can have one or many railway=stop (not rendered) associated with them.

Before/after:

[Pengor]

Fine by me, unfortunate this tag isn't used consistently in different places, but oh well 🤷‍♂️