Also, add two missing configure options, and frob some other things.

It complained of "Unbound key" until now.

That is: nest the conditions consistently.
And in the bargain rename the variable.

Also, mention that help texts can now be searched through, update
a copyright notice, and update and simplify a copyright year.

And in the process transform the token DISABLE_HELP to ENABLE_HELP.

This avoids applying the default syntax, or the syntax specified
with --syntax, to a ^G help text.

And allow 'N' for searching the next occurrence.  Add the
same keystrokes to the file browser too, for consistency.

Since the help text is searchable, an <End> would go to the end of the
text but would leave a blank line above the statusbar -- a blank line
that wasn't there before, and that is not reached when simply holding
down <Down> all the way from the top.

So that the shortcut explanations get properly aligned.

When nano has multiple files open, closing a help buffer should
not switch to the next buffer in the ring but to the preceding one,
because it was from there that the help screen was invoked.

Also, save and restore all the flags in a single swoop.

There is no need to restore NOREAD_MODE after unsetting it, because
any files mentioned on the command line have already been /not/ read.

However, prefer moving the starting point of the text backwards over
moving it forward, so that of the same paragraph more text is shown
instead of less.  But scroll an empty line out of view -- no text is
"lost" then.

The top-left corner changing is far more conspicuous than the top right.

Allow the user to search in a help text with ^W and M-W.

Achieve this by not writing the help text directly to the screen
but first writing it to a temporary file and then opening this file
in a new buffer, and treating it specially: the normal file-reading
feedback is suppressed, the titlebar shows the headline of the text,
the cursor is hidden, and the menu is limited to just the up and down
movements and searching.

This fulfills https://savannah.gnu.org/bugs/?28994

.
Signed-off-by: Rishabh Dave <rishabhddave@gmail.com>

This fixes https://savannah.gnu.org/bugs/?50872.

The go_back_chunks() function will do this clipping.

This fixes https://savannah.gnu.org/bugs/?50866.

And make the strings after "start=" and  "end=" more readable.

Mention some things that really set nano apart from Pico.
Plus some other small tweaks here and there.

Call something a buffer when it refers to a linked list of linestructs,
and call something a linestruct when it is a struct that describes a
single line.

Trim a superfluous assert too.

Also avoid an unused-variable warning, and trim a useless assert.

It takes almost no code and is a useful little improvement over Pico.

File formats, appending and prepending, and backups are not available
when --enable-tiny is used, so prevent all relevant pieces of code from
getting compiled.  And correct two misspelled ENABLE_TINY to NANO_TINY.

And in the bargain avoid a duplicate call of strlenpt(prompt).

Because nothing gets reset to zero or to some initial value.

To avoid an ncurses hiccup (miscoloring) when running on musl.

This fixes https://savannah.gnu.org/bugs/?50787

.
Reported-by: Avi Halachmi <avihpit@yahoo.com>

The cursor needs to be placed in its proper spot in the edit window
/only/ when nano is about to accept input from the user and needs to
show where this input will go.

(This might cause a scrolling issue to appear, because reset_cursor()
does not just place the cursor, it also recomputes current_y, which
is used in several places to determine whether and how much to scroll.
If it so happens, we'll deal with that fallout later.)

Furthermore, change an item header into a question, swap two items,
and tweak the formatting a bit.