0.20: Unary, Binary, Ternary

Added

• --cache-builds flag (off by default for now) to cache builds locally (#1489). Thanks @baek-jinoo, @jasonboyle, and @BobElDevil!
• Support for .tar.gz binary archives (#1786). Thanks @dcaunt!

Improved

• Pre-built Swift binaries will only be used if they were built with the same version of the Swift compiler (#1755). Thanks @scottrhoyt!
• Carthage projects will be built with individual, per-version DerivedData directories (#1419). Thanks @ikesyo!
• The .pkg installer will no longer let you install to volumes without macOS (#1772). Thanks @dcaunt!
• Submodules checked out with Carthage will get symlinks for their dependencies (#1715). Thanks @jdhealy!

Fixed

• The PackageInfo for the .pkg install will have the correct version (#1773). Thanks @mdiep!

Thank you to @johnmckerrell, @dcaunt, @louisdh, and @scottrhoyt for improvements to documentation. Thank you to @ikesyo for improvements to the codebase. Thank you to @mdiep and @NachoSoto for reviewing pull requests.