OpenVMS support (very low low priority)

[plicease]

has always been mentioned in the documentation, but as I updated it, I don't think it has ever been tested or used. It would be an interesting exercise to figure out if it is possible or even useful. Found this interesting:

https://stackoverflow.com/questions/38989770/what-is-equivalent-command-of-unix-which-in-vms

https://metacpan.org/source/BINGOS/IPC-Cmd-0.98/lib/IPC/Cmd.pm#L228

[plicease]

We can re-open or open a new ticket if this ever becomes relevant.