A client joining a game on a map it does not have (a Custom Edition map
not in custom_maps, or one of the game's own not in maps) now leaves with
an error naming the map and where to copy it, instead of the damaged disc
error. It also says when the map cannot run there or the host names a
Custom Edition map as other versions do. The port's error texts wrap to
their dialog, in the smaller font when they would not fit.
Network version 22: hosts now name Custom Edition maps custom_maps\<name>,
which older clients cannot load or explain; they are told to update.