Point exploder, first cut

This is a first cut at the point exploder, that splices into the upload chain to explode a PolylineM shoreline shapefile with associated uncertainty DBF into a Point-by-Point shapefile with per-point uncertainty.

Code is not final -- needs cleanup and tests, at the least.

Question:
* Should original shapefile be published as well, for use in map display?  This would require modification to the process for publication to geoserver, which this code pre-empts for the point-by-point shapefile