Pyraf for Python 3

Following some collaboration with the IRAF Community project earlier this year, we are pleased to make available PyRAF 2.2.1, the first version to pass all our testing on Python 3. This runs roughly as fast as the Python 2 version, thanks to improvements by Ole Streicher.

This version is already included on the new IRAF VM for Apple machines (see announcement above). On Linux, it can be installed by specifying "python=3.7" instead of "python=2.7" in the "conda create" command. For instructions, see here.

Linux builds are also available for Python 3.8 & 3.9, but using 3.7 allows you to install it alongside the current public DRAGONS version. PyRAF 2.2.1 is NOT compatible with Python 2, where the latest version will remain at 2.1.15.