use MatGemini 3.x API

Specifically, the khi_periodic_lowres and gdi_periodic_lowres were updated to use the "package" API of MatGemini 3.x. This means one no longer has to add numerous paths to the Matlab path--just the toplevel MatGemini directory needs to be on Matlab path. This is accomplished by running setup.m at the top of this repo.

for legacy MatGemini v2.2 api

making a release that works with legacy (pre-import) v2.2 MatGemini api

KHI JGR paper

Andres et al, 2020