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.

* implement conda package building

* paths

* need libtool

* PLATFORM check

* point to my PROJ feedstock for now

* point to PROJ repos

* plot building and artifact upload

* syntax

* add proj conda package for plotting

* retab

* no doxygen

* syntax

* update docs Makefile

* doc building

* needs

* consolidate doc/plots

* plot updates

* put updated plot output into docs

* register spelling module

* use v2 download-artifact

* artifact upload

Limit peirce_q to northern hemisphere, and fix images for adams_hemi, guyou and peirce_q

- The current implementation of the Interrupted Goode Homolosine
  projection emphasizes land area. This is a compliment projection
  that emphasizes ocean area.
- A value of lon0=-160 produces a reasonable real-world map.

This commit adds five new projections to PROJ:

    adams_hemi: Adams Hemisphere in a Square
    adams_wsI:  Adams World in a Square I
    adams_wsII: Adams World in a Square II
    guyou:      Guyou
    peirce_q:   Pierce Quincuncial

The code originates from Gerry Evendens libproject and has been adapted
to work with modern PROJ. To ensure that the modified code works as
intended extensive test data has been created using libproject and
sproj so that no errors occured when porting from libproject to PROJ.
The test data is wrapped in a gie files. All test cases reproduce
results from libproject at the mm level.

Add Tobler-Mercator projection