contrib mdoc: reorder sections consistently
contrib mdoc: fix typos in macro names

Found by:	mdocml
contrib mdoc: quote special chars to avoid empty macros
contrib mdoc: use correct macro to print backslashes
contrib mdoc: remove duplicate paragraph
contrib mdoc: fix broken macro usage
contrib mdoc: balance quotes
contrib mdoc: fix typo in date
contrib mdoc: Unbreak mandoc (and groff) rendering

form_field_opts.3, ippool.5 and editmap.8
were broken for groff, too.
mdoc: quote some special chars

This avoids empty macro warnings by mdocml
mdoc: fix .Bl -column lists to only contain .It elements

Found by:	mdocml
mdoc: unroll custom list header macro

Also make sure each line in the -column list is an .It element, fixing
rendering with mandoc.
mdoc: use correct macro to print backslashes

Found and complaint by:	mdocml
mdoc: refactor column "tables" into something more readable

This is also necessary for mdocml to grok what's happening