Arti 1.2.2 is released: onion services development

Arti is our ongoing project to create a next-generation Tor client in Rust. Now we're announcing the latest release, Arti 1.2.2.

This release continues improvements to the security of onion services (for example, Arti now supports Vanguards for improved security against guard discovery for onion service circuits). It also fixes a few bugs, such as #1379. Even more security improvements are on the way. See doc/OnionService.md for instructions and caveats about running onion services with Arti today.

Also, we've overhauled the configuration reader to use figment, and we're picking up the pace on the planned RPC system, which will allow Arti to be managed and controlled programmatically.

For more information on using Arti, see our top-level README, and the documentation for the arti binary.

Thanks to everybody who's contributed to this release, including Alexander Færøy, Jim Newsome, Richard Pospesel, trinity-1686a, Wiktor Kwapisiewicz, and VaiTon.

Also, our deep thanks to Zcash Community Grants and our other sponsors for funding the development of Arti!