When giving a line number on the command line, do_gotolinecolumn() needs
to know the width of the screen to be able to (roughly) place the target
line in the center of the screen.

This fixes https://savannah.gnu.org/bugs/?49462.

This fixes https://savannah.gnu.org/bugs/?49423.

Also remove some cluttering conditional compilation.

Also, don't bother conditionalizing two booleans for the tiny version.

The nanorc option already exists, but not the corresponding one
for the command line.

This fixes https://savannah.gnu.org/bugs/?49428.

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.

Also mention the corresponding toggle (M-#).

This fixes https://savannah.gnu.org/bugs/?49406.

There is no need to look at this for every painted line, because
the margin can only change when some key is struck.

Instead of doing this in two places: after interpreting shortcuts,
and after injecting characters.

To prevent the display from getting messed up, making nano unusable.

It can be activated with --linenumbers on the command line or with
'set linenumbers' in a nanorc file, and it can be toggled with M-#.
Signed-off-by: Faissal Bensefia <faissaloo@gmail.com>
Signed-off-by: Benno Schulenberg <bensberg@justemail.net>

Instead of figuring them out from the string.  This is possible
because those dedicated editing keys cannot be rebound anyway.

This fixes https://savannah.gnu.org/bugs/?49099,
and fixes the unreported corresponding bugs for
<End> and <Del> and typing extra characters.

So the softwrap code in do_down() can compute the correct amount to scroll.

This fixes https://savannah.gnu.org/bugs/?49374.

This fixes https://savannah.gnu.org/bugs/?49058 reported by Rishabh Dave.

This fixes https://savannah.gnu.org/bugs/?49106.

Also, show in green only the ^ and M- combinations that are valid.

This fixes https://savannah.gnu.org/bugs/?49097

.
Signed-off-by: Rishabh Dave <rishabhddave@gmail.com>
Signed-off-by: Benno Schulenberg <bensberg@justemail.net>