When also --nohelp is active and the terminal is so narrow that the
message that --constantshow displays on the bottom row does not fit,
this causes the cursor to be pushed "offscreen".  Some terminal
emulators don't handle this case correctly, and leave the cursor
in an invisible or mistaken position.  Compensate for this by
moving the cursor back to the start of the row.

This fixes https://savannah.gnu.org/bugs/?51335

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

The extra variable is not needed, because when having read from
standard input, the filename will simply be empty.  It will not
be empty for any other file that was read.

The dash doesn't have to be the first non-option argument: it can
be anywhere among the filenames -- there can even be multiple ones
(but don't mention this explicitly).

Negative arguments of 'fill' are bright green since a few commits.
So now color all valid numeric arguments in that same style -- the
yellow was hard to see on a dark background anyway.

Also, color a zero tabsize as invalid.

This partially adresses https://savannah.gnu.org/bugs/?50998.

Especially: get rid of the "Up: (dir)" link that points nowhere.

Also, add a horizontal line before the final Table of Contents.

They can be given at the prompt, so it's better to accept them on the
command line too.

Also improve some comments.

And rename the function while there anyway.

A recent change (8dffb00f) removed this ability.  This change restores
it, and also allows reading from standard input multiple times -- maybe
not useful, but it works.

Also, conditionalize a statement that is only effective when
multiple file buffers are available.

Also, shorten two variable names.

This reduction is possible since the routine no longer loops when
it encounters a +NUMBER argument.

Also when a dash is the first "file" mentioned on the command line,
nano should show this buffer at startup and not the next.

This fixes https://savannah.gnu.org/bugs/?51207.

This fixes https://savannah.gnu.org/bugs/?51208.

This fixes https://savannah.gnu.org/bugs/?51206.

Reading from standard input is a purely sequential affair --
no need to split it into two functions.

In the tiny version, Ctrl+Left and Ctrl+Right are available only
in the editor itself and in the file browser.

This fixes https://savannah.gnu.org/bugs/?51173.