Documentation and help improvements:
* userv(1) manpage: fixed broken definitions of fd excl and trunc.
+ (Debian bug report: Closes: #79579.)
* Specification's usage notes section improved.
* --help and --version behaviour made to conform to GNU standards.
* We do ship m4 and flex output now, so say so.
+ * Some groff warnings in userv(1) fixed.
Debian:
* Priority changed to optional as per override file.