Create a tagged version (geojson) of selected GMNS tables

[ssmith55]

The initial requirements for GMNS did not resolve the question of tagged vs. delimited format. GMNS Is currently using a delimited format, with well-known text (WKT) for geometry information. Some applications may prefer a delimited format (geojson).

Basic conversions of the link and node tables were tested using QGIS. The process is straightforward: export the layers in question as geojson. Other tools may also exist.