PROJ API

[Olly Betts]

On Wed, Sep 08, 2021 at 09:25:29AM +0100, Mark Shinwell wrote:
> What about vendoring the old version of proj into the Survex tree for the
> time being?

That doesn't seem a good use of effort - better to get the new PROJ
working since we'll need to do that longer term anyway.

The only remaining blocker now seems to be that I can't get grid
convergence calculations to work with the new PROJ.  I'm going to
make a small, self-contained reproducer and (unless doing that
reveals I'm doing something wrong) ask the PROJ developers.

One bonus is that the heights from terrain data now match up much
better (at least for the CUCC Austria data set).  Looks like PROJ
now takes the vertical datum into account automatically.

Cheers,
    Olly