Shared stack updated to use rubin-env

I have updated the shared stack on the NCSA shared computers to use the new rubin-env described here.

Sourcing the setup scripts from the path /software/lsstsw/stack/ as before will automatically get you to the current version. /software/lsstsw/stack3/ will also get you to the same location, but it has been a while since switching to python 3, so it might be a good time to update your shell scripts if you are still using that link.

For those of you who prefer the direct path to the new stack location it is found at /software/lsstsw/stack_20210114. I have built weeklies 1,2, and 3.

If you need weeklies from last year, you can find the old stack at /software/lsstsw/stack_20200922. Keep in mind the new stack is on python 3.8, and so the master version of a repo, or newly developed code may not work against any old stacks. As such, they likely should only be used for investigation or reproduction.

I have run some tests, but if anyone sees any issues with the new environment, please report it.

Have fun (responsibly) with your new Python 3.8 environment.