[Therion] Export EE as .3D and ignore "survey does not exist"

[Tarquin Wilton-Jones]

> 1) Is it possible to export an extended elevation as a 3D file (like
> survex does)? For the purpose of 'debugging' the extends etc.

I doubt this is entirely possible. There are some kinds of extend
options that Therion supports but Survex does not, such as "extend
vertical". So I don't think you could turn it into a Survex-style 3D if
you use those options.

I usually export it to PDF to see how it renders.

You could also export it as a Therion XVI (since that's what you will
end up using anyway) and import that into a .th2 to see how it looks.