(Hooray for nano's regex replacements.)

This fixes https://savannah.gnu.org/bugs/?49824.

Since do_mouse() uses edit_redraw(), openfile->current_y will be
immediately recalculated, so there's no point in changing it now.
Use a temporary variable instead.

The value of sameline doesn't change, so it can be initialized to that.

Since i holds openfile->current_y, it should be ssize_t, not size_t.

And it's better to do the most significant part of a calculation first.

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.

This makes nano's cursor behavior consistent across 1) typing text by
hand; 2) pasting in text with ^U; 3) inserting text from a file; and
4) redoing with M-E that same typing or pasting or inserting.

This fixes https://savannah.gnu.org/bugs/?49968.

This fixes https://savannah.gnu.org/bugs/?49964.

This fixes https://savannah.gnu.org/bugs/?49962.

They are not documentation, they are functional elements of nano.

There are just a handful of source files for the documentation --
it is wasteful and cumbersome to have these in separate directories.

Also: remove the French man pages -- they are too far out of date.
(And anyway, we should acquire a general framework for translating
the documentation.)

URL: https://bugs.gentoo.org/604000

The warning is wrong when the user has just saved a buffer under a
new name.  And when --quickblank is used, the warning most likely
gets cleared off before it is seen, and the user would just hear
the beep and be left wondering what happened.

This avoids https://savannah.gnu.org/bugs/?49875.

This disallows entering a verbatim ^J (0x0A) when typing text or
search terms, and disallows a verbatim ^@ (0x00) when typing a
filename.  Nano beeps when the disallowed code is attempted.

This addresses https://savannah.gnu.org/bugs/?49897.

A KEY_WINCH does not need to be separately treated since the basic
action for anything that is not recognized at the yes-no prompt is:
to continue.

Also at the yes-no prompt, a 0x0A byte should be displayed as a ^J
instead of splitting the prompt bar in two and spreading it over
two lines.

This fixes https://savannah.gnu.org/bugs/?49934.

When a given file is, for example, unreadable or unwritable, the
error message should use ^J instead of ^@ in its name.

This fixes https://savannah.gnu.org/bugs/?49933.

After a call to the Formatter or the Alternate spell checker, the data
on the undo stack could refer to line positions that don't exist any
more -- the chance is small, but it is there.  So... throw the whole
undo stack away, to prevent undoing things wrongly or even crashing.

(Changes made with the internal spell checker can be undone and redone
without a problem -- nano keeps full track of those.  But the changes
made with a formatter or an external spell checker happen in another
process, so nano has no record of them.)

This fixes https://savannah.gnu.org/bugs/?49920.

When using an external spell checker or formatter, the line with
the cursor might become shorter, which might result in the stored
cursor position being beyond the end-of-line.  So, when restoring
the x position, make sure to limit it to the length of the line.

This fixes https://savannah.gnu.org/bugs/?49923.