shellcheck

USE flags

• doc - Add extra documentation (API, Javadoc, etc). It is recommended to enable per package instead of globally
• hscolour - Include coloured haskell sources to generated documentation (dev-haskell/hscolour)
• profile - Add support for software performance analysis (will likely vary from ebuild to ebuild)
• test - Enable dependencies and/or preparations necessary to run tests (usually controlled by FEATURES=test but can be toggled independently)