This issue is to track progress on adding support for OSMM Highways Network. WIP config notes can be found on the wiki: [Ordnance Survey OSMM Highways Network to PostgreSQL/PostGIS](https://github.com/AstunTechnology/Loader/wiki/Configuration-examples#ordnance-survey-osmm-highways-network-to-postgresqlpostgis). Note: 016624f or later is currently required to use the `--config GML_GFS_TEMPLATE $gfs_file` option within the `ogr_cmd`. /cc @archaeogeek