building yardl on MacOS

[KrisThielemans]

There are a few issues:

• environment.yml:
  • contains lots linux packages. I had to remove them.
  • conda-forge MacOS also doesn't seem to have node.js at that version, so I deleted that as well.
  • it doesn't include go
• Typing just gave an error with like

  mkdir .../matlab/generated/+yardl: file exists
  

• Doing just install didn't do anything. I had to do set GOPATH first (possibly because I installed go via conda in the existing environment without reactivating it.