Design "workflow" interfaces

[cvogt]

maybe we should not put top-level methods compile, test, package etc into the base build. They are somewhat biased. Instead we can have the default bias free, but instead have interfaces that patch those methods on top without forcing anyone to use them.

[cvogt]

Maybe the workflow can be biased even towards language. E.g. one workflow could be the ScalaBuild, which then has biased tasks like compile, sets the target like sbt's, the src directory to src, etc.