As I noticed a lot of missing information when trying to implement checking
for missing info. I reimplemented the version information script to be more
robust, and here is the result.
Follow up to ec07c3c80b
This tries to add information about when each option was added. It goes
back to version 183.
The version info is included from a separate file to allow generating it,
which would allow more control on the formatting of the final output.
And while we are at it, make 'ssh-authorized-keys' verb properly
documented. Given that OpenSSH documents the interface in its man page
it's fine to just document our implementation of it too.
I started working on a command-line switch to show passwords also in
"pretty" mode. I can submit that code for review if anyone thinks that
woul be useful, but after writing the man page I realized that it's a
fairly niche case, and the hint in the man page is a sufficient
replacement.
