announcing QGIS3 plugin to import survex .3d files

[Patrick Warren]

Just to say I've migrated my existing .3d import plugin to work with QGIS3,
see:
https://github.com/patrickbwarren/qgis3-survex-import

I haven't tried it on windows though.  Any problems let me know or file an
issue report.

Features:
 - no dependencies, natively reads binary v8 format survex .3d files;
 - import stations and legs with full metadata;
 - create passage walls, cross-sections, and polygons from LRUD data;
 - all features have z dimensions, and (mean) elevations to assist coloring;
 - CRS can be set from PROJ.4 string embedded in .3d file;
 - results can be saved immediately into a GeoPackage (.gpkg) shapefile.

Patrick