Adams Square II: map ESRI WKT to PROJ string, and implement iterative inverse method

[rouault]

• Tests added
• Added clear title that can be used to generate release notes
• Fully documented, including updating docs/source/*.rst for new API

[rouault]

Inverse projection is needed for gdalwarp for example:

$ gdalwarp -r cubic ../autotest/gdrivers/data/small_world.tif /tmp/out.png -t_srs "+proj=adams_ws2" -overwrite
Creating output file that is 447P x 447L.
0...10...20... 30...40...50../tmp.60...70...80../out.90...100 - done.

[nyalldawson]

Nice -- I was just building master to see if I could map these new ones! Did you look into mapping Peirce_Quincuncial yet?

[kbevers]

Looks good to me. I like the generic approach to the inverse adams_ws2, good thinking!

[rouault]

Did you look into mapping Peirce_Quincuncial yet?

no. Not sure I'll do

[busstoptaktik]

Hooray! This is awesome @rouault!

@kbevers: I see from your comments that you consider making this a generic fill-in for one-way projections, which is even more awesome. If you should succeed, consider making the core derivative computations part of derivs.cpp/pj_derivs().

Also, the material covered in factors.cpp may give some insight in how perversely deform the projected space may be locally.