CMake build system

[timothyschoen]

Replaced Makefile system with CMake system, which makes it a lot easier to have sub build systems. It also:

• Simplifies and speeds up github actions build
• Allows you to generate any build system you like: Makefiles, Ninja, Xcode project, Visual Studio project, etc.
• Prepares a complete ELSE release by regularly building
• Builds universal binary on macOS by default
• Can easily change the output dir, and will apply to all objects
• Keeps externals and .o files out of the rest of ELSE files, since they will all be in the cmake build folder. I also added things to .gitignore that should never go to version control.
• Builds else's shared files into a single dynamic library to save space
• There are no more pre-built dynamic libraries or dependencies. Everything you need is in the repo

I also generally cleaned up the github actions, and did some small directory restructuring.

[timothyschoen]

After some more fixing, I can now open All_objects without any errors, so I think this should be good!