'RELENG_4_0_0_RELEASE'.

This commit was manufactured to restore the state of the 4.0-RELEASE image.
Releases prior to 5.3-RELEASE are omitting the secure/ and crypto/ subdirs.

of the typeset output, tend to make diffs harder to read and provide
bad examples for new-comers to mdoc.

calculation of line numbers) never existed and the two bugs that made me
think it existed have been fixed (see recent commits about this date to
linenum.c:r.1.3 and ch.c:r.1.8 fixing broken line-number buffering and
braindead algorithms respectively).

simply keep an index into the last access on the circular list and begin
searches at that point.  An LRU list is inappropriate here since the
vast majority of accesses will occur in the same order that the list
is created in.  The only case where an LRU is remotely useful here is when
reading from a file and the user is jumping to randomish positions and
constantly returning to some central position.  Even for this case it is
such a small optimization as not to be noticed in an interactive program
such as more(1).

This change results in a _tremendously_ noticable speed-up when reading long
files through a pipe (where long = ~200k, machine = ~2.5h single-disk
worldstone).

bug that prevented the line-number buffer from working correctly.  AFAIK
the bug is still present in other derivatives of more(1).

the docs on a couple other keys.  While I'm here, document another ~3 bugs
that have been around for all eternity in the hope that I'll someday bother
to fix them.