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, 16 insertions, 0 deletions

diff --git a/regress/man/IP/vert.out_ascii b/regress/man/IP/vert.out_ascii
new file mode 100644
index 00000000..428733be
--- /dev/null
+++ b/regress/man/IP/vert.out_ascii
@@ -0,0 +1,16 @@
+IP-VERT(1)                  General Commands Manual                 IP-VERT(1)
+
+
+
+NNAAMMEE
+       IP-vert - vertical spacing before indented paragraphs
+
+DDEESSCCRRIIPPTTIIOONN
+       tag    text
+
+
+       tag    text
+
+
+
+OpenBSD                        February 19, 2020                    IP-VERT(1)