(svn r6789) - Codechange: Tidy up VehicleNameSorter() to use no global vars, and match the style of EngineNameSorter(). This also removes a bug where _internal_name_sorter_id was never set properly for anything other than trains.

/* $Id$ */

KNOWN BUGS / PROBLEMS:

Normal and elrail depots look the same. Use 'X' (transparent buildings)
   to distinguish between them
Missing curors / icons for construction (currently using the conventional ones)