Allow public/ to be a repo with gh-pages branch

[#69018126]
Land Mgmt: rm unused properties (sky|land)Patches

Not only are they not used, but @skyPatches wasn't being updated when patches were changed to sky during erosion.
Land Mgmt: Track topsoil status of eroded patch

[#67109678]
Land Mgmt: don't regenerate topsoil

[#67109678]
[#67110390]

Also makes subsoil slower to erode than topsoil
Fix apparent assignment-vs-comparison bug
Land Mgmt: Plant growth should be exponential

[#67110390]