Update to Cars REPO

[TomQD-94]

@newville When the master branch gets updated the method to install is not updated in relation to it. i.e the xspress3-2-x folder that is downloaded by the build script does not have updated files. Is there a way to automate this so that any master branch update gets put put into the repo and the file pulled by the build script is incremented?

[newville]

@TomQD-94 right, at the moment those come from releases (and me copying tarballs from github, so "explicit publishing"), not the current master. I think the main thing to do is make a new release. Do we think we are ready for that? I would say yes.

We could update build_xspress3.py to fetch the tarball from github...

[TomQD-94]

@newville I would say this is good for a new release. Perhaps there should be an option to pull it from github otherwise a simple bugfix would cause you to set up a new release, new tarball, and then update the script. Although I don't know how often new releases will happen

[newville]

@TomQD-94 OK, tagged and released 3.2.7. The latest build_xspress3.py should work, but I have not tested that yet ;).