GeoZero Shapefile driver

Reading Shapefiles with GeoZero API.

Planned functions: * Support for Multipatch types * Read spatial index

For writing Shapefiles either use shapefile-rs or the GDAL driver of GeoZero Core

Originally based on shapefile-rs from Thomas Montaigu.

Usage example

```Rust use geozero_core::geojson::GeoJsonWriter;

let reader = geozeroshp::Reader::frompath("poly.shp")?; let mut json: Vec = Vec::new(); let cnt = reader.iter_features(GeoJsonWriter::new(&mut json))?.count(); ```