Fix "new sentence, new line" warnings throughout so that formatters
can produce correct spacing between sentences.
Remove unnecessary Ns macros. These are not necessary for delimeters,
which get special treatment.
Fix date in manual. The contents were last modified on 2016-12-03,
so use that instead of the invalid date.
Fix escape sequence for `\<` and `\>`.
Remove spurious `\\n` escape for the null-command.
The one specified by mdoc is hard to read for non-native
speakers from countries which read the date day-first (like
Germany, Greece, North-Korea, Swamp,...).
This is also consistent with how we generally specify dates
Mostly manpage-shuffling according to the changes in the corrigendum,
wording changes and more idiomatic expressions.
All this is finished up by marking the POSIX 2013 conformant tools
which is not available in older mandoc builds or nroff, but which
reflects what we actually did, so who cares?
This is a huge step and it's not far until we can release sbase 0.1.