Testing:
  Add Sass support for various utilities (benchmark, profile)

Documentation:
  ! Document Sass module
  Haml::Engine public method info could use work

Features:
  Exceptions thrown by Sass code should have their own class
  Exceptions in general should be a lot nicer
  Filters for Haml
  Haml and Sass should throw syntax errors rather than blithely parsing ill-formatted documents
  There should be a way to represent options in-document
  Haml and Sass executables should return meaningful exit codes