Export formats

[Olly Betts]

Currently aven supports exporting to the following formats:

* DXF - CAD format (also via cad3d)
* EPS - Encapsulated PostScript - a vector image format
* GPX - for importing to GPS units
* HPGL - for plotters
* JSON - experimental export for web-based viewers
* KML - for use with GIS systems, online map sites, etc
* PLT - intended for use with Carto (also via cad3d)
* POS - produce a Survex .pos file (also via 3dtopos)
* SK - Skencil format (also via cad3d)
* SVG - vector image format e.g. used by inkscape (also via cad3d)

I suspect some of these are no longer used.  For example, Skencil is an
open source drawing package which last saw any development in 2010 from
what I can see: http://skencil.org/, though perhaps other tools use the
format.  Carto seems inactive too (last release 2005).

I'm not proposing to drop any formats currently, but it would be useful
to know which formats are actively used to focus effort when making
enhancements to the export functionality.

Some enhancements pretty much automatically work for all the formats
(for example, allowing hiding of splay legs), but others need some work
for each format (for example, showing splay legs but in a different way
to non-splay legs), and working on these for a format nobody uses up
time I could spend working on something else.

Also, are there any formats missing from the list people would find
useful?

Cheers,
    Olly