WISHLIST:
- cross-compiler support
- "Simple Packaging Kit" output support see
  http://developer.stampede.org/system/spk/
  (as a frontend and a backend... maybe)
  (also: need to decide if we should `spk_build' or just
  implement it ourself w/ tar and bzip2..)
- automatically add conflicts if file sets intersect

-- Error checking / handling.
 Here are conditions to assert (which will cause hard to diagnose
 failures later on)
  - Manpages have valid sections.
  - Source-Docs and Docs don't actually refer to the same destination file.
  - Target names are unique
 Conditions which are bad but not fatal:  warn about them.
  - installed files that are never used.