[PROJ] Axis ordering and proj_trans

[Nyall Dawson]

Hi list,

It's my interpretation of reading the docs that when calling
proj_trans the order of values in PJ_COORD.v must match the expected
axis order (when using EPSG codes for the transform parameters).

What's unclear is if this **doesn't** apply when calling
proj_trans_generic? Is it safe to assume that for proj_trans_generic x
is ALWAYS x (or longitude), y is ALWAYS y (or latitude), etc?

And on a related note: For one-off, single point transforms, is it
preferable to use proj_trans? Or is it equally efficient to use
proj_trans_generic with one element arrays?

Nyall