This fixes the current forward implementation of Peirce Quincuncial proj to correctly flip/reflect out the southern hemisphere to four triangles, and rotate entire result to a square or diamond. (It there resolves the issues identified with pull request https://github.com/OSGeo/PROJ/pull/2230 , where southern hemisphere was wrongly projected over northern, and reverses the restriction to northern hemisphere introduced there). It also adds additional lateral projection of the hemispheres.

- This PR adds an optional parameter `+type` which allows selection of projection. The `+type=square` and `+type=diamond` types match in principle ESRI's twin implementations of square and diamond PQ projs. The **default** if not specified is `+type=diamond`.

- The previous behaviour restricted to the northern hemisphere can be reproduced using the `+type=nhemisphere`, though this is an edge case only.

- An additional `+type=horizontal` and `+type=vertical` rectangular lateral versions have been added that place each hemisphere side-by-side. This is primarily to allow creation of projections such as Greiger Triptychial, which also require the additional optional params `scrollx` or `scrolly` in order to shift parts of the projection from one side of the map to the other. 

- Additional documentation has been added to proj description, including quoting the usual meridian used in common usage of projection, and images showing the different types.

Fixes #2482

And also add proj_context_errno_string()

Revise gie 'expect failure errno XXXX' strings

Gone are pj_malloc, pj_calloc, pj_dalloc and pj_dealloc. Their primary
function as API memory functions in proj_api.h is no longer there and
the other use as a workaround for old errno problems is no longer valid
either.

Replaced with malloc and free across the codebase.

- Move the generic method initiated from adams_ws2 to a
  pj_generic_inverse_2d() method
- Use it in adams_ws2
- Use it in wink2

Fixes https://github.com/qgis/QGIS/issues/35512

Otherwise it returns junk (negative latitudes are mapped to
the same location as positive latitudes)

I'm a bit confused by PROJ peirce_q implementation. Looking at
the projection of the world, it looks like this matches the diamond
formulation of the right map shown at
https://desktop.arcgis.com/en/arcmap/latest/map/projections/peirce-quincuncial.htm,
but limited to the inner square of this diamond (which corresponds
to the northern hemisphere). We lack the 4 triangles on left, top,
right and bottom for the southern hemisphere. Furthermore, this
formulation of peirce_q does not seem to have the quincuncial
property of the square formulation (left images of the above ESRI
doc), or the one at https://en.wikipedia.org/wiki/Peirce_quincuncial_projection ...