Moving ICESat/ICESat-2/OIB scripts to separate repositories

[tsutterley]

Could make the pyTMD repository skinnier by dropping some dependencies. Not sure if anyone else is using those programs. Suggestions?

[mrsiegfried]

I actually really like having these in there. But I'm totally biased. They maybe do belong elsewhere in a more altimetry focused repo... 🤔

[lyingTree]

I think you are right. Those scripts should belong to another repository
Because they are not related to the purpose of this repository.

[tsutterley]

Okay, I'm making this shift. IS/IS2/OIB codes will be a separate repo called Grounding-Zones.