Add a section on security considerations
The section on security considerations sheds some light on the problems that we
can't solve within slock but which the user has to solve in his X configuration.
Convert manpage to mandoc and fix usage
In all honor, the previous usage was formally more correct, but for the
sake of consistency across all the tools having the v-flag, I separated
it from the command-string.
Also, make use of the mandoc macros for the manpage. This makes it
easier to maintain, extend and change in the future.
Revert "No need for usage()"
This reverts most of commit a6dc051e3744ce5b14c54d2d246d3e8258207e76 and fixes
some related stuff:
- keep spelling fixes from original commit
- make -h and -v also work when followed by more arguments
- any unknown flag prints usage
- fix output of -v to display "slock: version 1.3" instead of "slock: slock-1.3"
No need for usage()
There are 2 arguments why -v and -h are broken:
1) if you are running off git, -v will show the last stable
release, effectively making this option useless.
people running stable versions leave open an attack surface
this way in case there are vulnerabilities found.
99% of the people are also using package managers to keep
their software up to date, instead of running $TOOL -v to
check how old it is.
2) -h is a sad excuse for not just looking at the manual page
(man 1 slock). Given we accept a post_lock_command, we can't
be as liberal and just intercept certain flags.
I changed the manpage to reflect this change.