To install the stable version use:
sudo snap install openbabel
To install the development version use:
sudo snap install openbabel --channel=edge
You can switch between them with:
sudo snap refresh openbabel --channel=stable # or edge
To see which you have installed, use "snap list", or run "openbabel.obabel" and look at the version number and date.
Notes: I'm using Launchpad to do this. Rather than base it directly off the openbabel master (which would require me to check-in snapcraft specific files), I've set it up so that it runs off a branch (named "snaps") in my own repo. Every so often, I merge master into this and a new snap will be created. To fully automate it, I will need to have a cronjob to do that merge automatically.