Introduce the concept of nodes that are semantically transparent:

they are skipped when looking for previous or following high-level
macros.  Examples include roff(7) .ft, .ll, and .ta, mdoc(7) .Sm
and .Tg, and man(7) .DT and .PD.  Use this concept for a variety
of improved decisions in various validators and formatters.

While here,
* remove a few const qualifiers on struct arguments that caused trouble;
* get rid of some more Yoda notation in the vicinity;
* and apply some other stylistic improvements in the vicinity.

I found this class of issues while considering .Tg patches from kn@.

1 files changed, 14 insertions, 0 deletions

diff --git a/regress/man/SH/vert.out_ascii b/regress/man/SH/vert.out_ascii
new file mode 100644
index 00000000..f8afd7e0
--- /dev/null
+++ b/regress/man/SH/vert.out_ascii
@@ -0,0 +1,14 @@
+SH-VERT(1)                  General Commands Manual                 SH-VERT(1)
+
+
+
+NNAAMMEE
+       SH-vert - vertical spacing of sections
+
+DDEESSCCRRIIPPTTIIOONN
+EEXXAAMMPPLLEESS
+       text
+
+
+
+OpenBSD                        February 20, 2020                    SH-VERT(1)