Migrate build definiton from `build.sbt` format to `Build.scala`.
Split project into `common`/`plugin` modules.
Use `PackageObjects` to enumerate `WartTraverser` objects.
Fix `WartTraverser` lookup.
Add trace information for `Settings.warts`.
Introduce `Selection` expression parser.
Add `build.properties` with explicit sbt version.
Enable `Selection` expression to choose warts.
Add `Suffix`.
Format dynamically warts error message to sound more human friendly.