A mass update removing the g.new_gnxs switch.  All tests pass.
As before, the new gnxs code should be compatible will all previous versions of Leo because  fc.createSaxVnode still calls NodeIndices.scanGnx, and that method should allow for old-style gnxs.
However, just to be safe the old gnxs code still exists as comments.
Commenting out the old gnxs code (rather than just disabling it with a switch) should help pylint issue more accurate warnings.