Releasing

1. Run versions = mash.release.prepareBuildSbt (updates build.sbt and calculates version numbers)
2. Edit CHANGELOG to add date
3. git.commit -a "Release $versions.release"; git.push
4. Create executable jar and deb package: sbt clean assembly debian:packageBin! (creates target/scala-2.12/mash-$VERSION.jar)
5. mash.release.createGithubRelease versions.release
6. sha = hash.sha256 "target/scala-2.12/mash-${versions.release}.jar"
7. cd "../homebrew-mash"
8. "mash.rb.template".read.replace '$VERSION' versions.release | .replace '$SHA' sha | write "mash.rb"
9. git.commit -a "Release $versions.release"; git.push