Log Message:
Update to 2.1.6

The changes from 2.1.5 are:

- Added pigz.spec to distribution for RPM systems [Brown]
- Avoid some compiler warnings
- Process symbolic links if piping to stdout [Hoffst?tte]
- Decompress if executable named "gunzip" [Hoffst?tte]
- Allow ".tgz" suffix [Chernookiy]
- Fix adler32 comparison on .zz files