Changes in version 1.22.2:
Newline characters are no longer allowed in file names even if
'--unsafe-names' is specified.

The file name is now printed escaped also when replaced into a shell command.

Changes in version 1.22.1:

Ed now departs from POSIX and ignores SIGPIPE to prevent commands like
'w !:' or ',!:' from terminating ed. A broken pipe is now detected as any
other write error. (Reported by Sergei Trofimovich).

Changes in version 1.22:

The shell escape command (!) now accepts line addresses to filter the
addressed lines through a shell command. (ex(1) style filter).
(Suggested by Shawn Wagner, Andrew L. Moore, and John Cowan).
