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.

The old praxis of calling total_refresh() upon a SIGCONT was confusing,
because the screen would look as if nano had returned from suspension,
but in fact the shell was still active.

Instead of calling total_refresh(), put a no-op key into ncurses' buffer,
so that, when nano actually does return out of suspension (through 'fg'),
this key will be read and discarded, upon which nano will go sit and wait
for the next key, just before which it calls doupdate().  The latter is
all we need to get the entire screen restored.

This also fixes https://savannah.gnu.org/bugs/?51131 for "tiny".

This fixes a secondary part of https://savannah.gnu.org/bugs/?51124.

When receiving a SIGCONT, don't call regenerate_screen() directly
but act as if a SIGWINCH occurred.  Also insert a dummy key, and
thus let the relevant input routine redraw the relevant subwindows.

Use KEY_F0 as the dummy key, as both Ncurses and Slang know it, and
it should normally do nothing at all.

This fixes https://savannah.gnu.org/bugs/?51124.

When we are in the file browser, browser_refresh() will take care of
redrawing the title bar and the file list, so total_refresh() should
leave those two subwindows alone in that case.

This fixes https://savannah.gnu.org/bugs/?51147.

Achieve this by making the suppression flag global, so that we can
just reset it instead of making an improper call of do_cursorpos().

This fixes the secondary part of https://savannah.gnu.org/bugs/?51134.

Also, remove a useless assert.

This fixes https://savannah.gnu.org/bugs/?51134.

This has been done already during signal_init().