swap RoadTypes enum to version given by Alberth, with StreetTypes and TramTypes, and methods to set / get / check those from the RoadTypes instance
substitute RoadNotTypes whilst patching, then replace later (RoadNotTypes won’t cause search term conflict with RoadTypes)
to patch RoadTypes, there are 78 places consuming RoadTypes enum
move the storage to m4 as part of this, and deprecate the two existing road/tram bits
most of the consumers of RoadTypes don’t look hard to patch
replace some checking of bits with ‘HasStreetType()’, ‘HasTramType()’ calls
do not at this stage try and handle multiple types of StreetType, TramType, assume only one of each
this is unfortunately quite a large patch
extend StreetType and TramType to support multiple types of each available (only one per tile)
support constructing multiple types
support incompatibility when routing
extend features to StreetTypes and TramTypes
catenary, with drawing support (bridges, tunnels etc)
blah
what is all the scripting support doing with RoadTypes?
??
split types in global construction menu
does this imply also splitting the construction toolbars?  Or leave it unified and use a flag, as now?
do this first, in a dedicated branch, to find out?