V Bug when decompressing directory with mix of
  compressed/uncompressed and wildcard *
  V Check if dest and source exist
- Fix overwrite prompt
  - Uses non-portable read(2, ...) call since
    stdin has been reopened.
  - With wildcards, stdin has been reopened 
    after first file!  Not sure how to fix.
  - Try reopening stdin.  Perhaps save before
    reopening as file.
- Test copystat()
  - Try read-only file
    - Doesn't delete old file.
  - Try archive bit