- Add a default "(none)" option for license and category. There are now no
  questions with no default except for the lib/exe question. For throwaway
  packages user can just keep hitting enter and get something sensible.
- Prune the list of suggested licenses (remove unversioned GPL, LGPL)
- Don't include extra-source-files or build-tools when they would be empty
- Improve the wording of the generated documentation for lib/exe fields