Just like when spell-checking, there is no need to wrap around when
doing replacements in a region, because a region cannot straddle the
buffer's edges.

This is the proper fix for https://savannah.gnu.org/bugs/?50158,
and fixes https://savannah.gnu.org/bugs/?50273.

After the changes to the search routine, it is no longer necessary to
take one step back before starting a replacement session.

This fixes https://savannah.gnu.org/bugs/?50147.

Even when a match falls within the marked region, this does not mean
that it is a true match when already the whole file has been searched,
because then this is the second time we find this match.

This fixes https://savannah.gnu.org/bugs/?50158.

The spell fixer does not provide a beginning line, so the search routine
should then not try to refer to any data of this line.  Also, since the
changes to the search routine there is no need any more to retreat one
step before starting to search for a misspelled word.

This fixes https://savannah.gnu.org/bugs/?50159.

When the user answered No to a replacement prompt, skip the match
at the current position, so we don't stay stuck there.

Also, when replacing in the backward direction, or the match is
of length zero, skip the match at the current position, to not
get stuck.

This fixes https://savannah.gnu.org/bugs/?50126

.
Reported-by: David Lawrence Ramsey <pooka109@gmail.com>

This also fixes https://savannah.gnu.org/bugs/?50137,
and refixes https://savannah.gnu.org/bugs/?48635,
and fixes https://savannah.gnu.org/bugs/?50144.

That is: remove the special treatment of BOW anchors, and instead make
regexes match against the whole line instead of against an artificially
shortened one, because the latter method creates ghost matches: matches
at the starting point of the search that aren't really matches when seen
in the context of the whole line.

This fixes https://savannah.gnu.org/bugs/?50030.

When the tail of a match falls outside of the marked region,
it is in fact not a match and should not be replaced.

This fixes https://savannah.gnu.org/bugs/?50136.

When a replacement happens right at where the cursor sits, the position
of the cursor should not be adjusted, because the real cursor position
is between the current character and the preceding one: the place where
the cursor is shown is in fact right /after/ the insertion point.

This fixes https://savannah.gnu.org/bugs/?50134,
and fixes https://savannah.gnu.org/bugs/?50135.

This fixes https://savannah.gnu.org/bugs/?50028.

A search should start at the place of the cursor, not one step beyond,
so that the non-word boundary between the current character and the next
will be found.  Starting one step beyond the current character, as was
done until now, would find the non-word boundary between the next and
the overnext character as the first one.

The search routine begins searching right after the cursor and behaves
as if the line starts there, which means that a beginning-of-word anchor
(\< or \b) will match there also when in fact the cursor is sitting in
the middle of a word.  To prevent finding a false match, verify that
for a regex that starts with a BOW anchor the found match is actually
the start of a word.

This fixes https://savannah.gnu.org/bugs/?45630.

The conditionalizing saved negligible amounts of space, of memory, and
of speed.

In that case setting the latter to TRUE is misleading.  So don't do that.

Many of the adjustments of the value of openfile->current_y appear to be
a holdover from the days when certain functions had to account for what
is now called STATIONARY scrolling mode, which depends on the value of
current_y.  Remove these adjustement where they are superfluous.

do_para_begin(), do_para_end(), and do_bracket_match() update the screen
through edit_redraw(), which uses either CENTERING or FLOWING scrolling
mode, so their setting of current_y is redundant and useless, as it will
be ignored and then overridden by the next call to reset_cursor().

findnextstr() is called by go_looking() [which calls edit_redraw(), see
above], and by do_replace_loop() and do_int_spell_fix(), which both call
edit_refresh(), which in this case only uses CENTERING scrolling mode
since focusing is TRUE.

(Additionally, the adjustments of current_y in findnextstr() and
do_bracket_match() use incorrect values when in softwrap mode.)

find_paragraph() doesn't need to save or restore current_y, because it
doesn't do any screen updates.  do_justify() calls edit_refresh() with
focusing set to TRUE, so it uses the CENTERING scrolling mode.

do_alt_speller() and do_formatter() do not need to save and restore
current_y, because they don't modify it in any way.

This addresses https://savannah.gnu.org/patch/?9197.

In path names and file names, 0x0A means an embedded newline and
should be shown as ^J, but in anything related to the file's data,
0x0A is an encoded NUL and should be displayed as ^@.

So... switch mode at the two main entry points into the "file system"
(reading in a file, and writing out a file), and also when drawing the
titlebar.  Switch back to the default mode in the main loop.

This fixes https://savannah.gnu.org/bugs/?49893.

At the very beginning of do_replace(), nothing has been changed
or initialized yet, so there is nothing to refresh or clean up.

This make tiny nano slightly less tiny, but makes the code more readable.

It does not update anything -- it just picks a new point from
where to start displaying the buffer.  All actual updating of
the screen is done by edit_refresh() and edit_redraw() and such.

This avoids https://savannah.gnu.org/bugs/?49298.

And also case-sensitive searches, backward searches, and searching again.

Mentioning "GNU nano" instead of "This program" and referring to the
website instead of to a postal address.

This fixes https://savannah.gnu.org/bugs/?48635.

The negatives are taken to mean: from the end of the file,
and: from the end of the line.

This fulfills https://savannah.gnu.org/bugs/?48248.

This fixes https://savannah.gnu.org/bugs/?48282.

Don't make it the responsibility of the executed functions to restore
the list of shortcuts of the edit window.  Just detect whether another
menu was displayed, and if so, redisplay the main menu.