The old option descriptions were all written at different times, and needed some consistency. This makes everything consistent between the help text, README, man page, and shell completions, and fixes some mistakes made when writing them.
This also adds the missing options to the man page, fixing #175.
Now when you do `--sort time` instead of saying "unknown option --sort
time" it will say "unknown options '--sort time' (choices: name...)"
with all legal options.
This also adds the legal values to the default help text.
The original options was becoming a bit unwieldy, and would have been even more so if I added the same amount of comments. So this commit splits it up.
There's no extra hiding going on here, or rearranging things within the module: (almost) everything now has to be marked 'pub' to let other sub-modules in the new options module to see it.
