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

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

The interval 2013-2017 for the Free Software Foundation is valid
because in those years there were releases with changes by either
Chris or David, and the GNU maintainers guide advises to mention
a new year in all files of a package, not just in the ones that
actually changed, and be done with it for the rest of the year.

Mention the ability to use <Tab> in the search history, the ability
to restore the cursor position when reopening a file, the ability to
read output of a command, and the lack of file-managing commands in
the file browser.

And slightly change the existing one for normal users.

And modify a few wordings too.

This addresses a followup of https://savannah.gnu.org/bugs/?50362

.
Reported-by: Mike Frysinger <vapier@gentoo.org>

Also, add two cross references: one in words, and one with a link.

Also, remove the special "+line,column" argument from among the options,
since it isn't an option -- put it in a separate paragraph instead.

If the system on which nano is configured does not have the 'makeinfo'
program installed, the prebuilt and packaged nano.info and nano.html
should nevertheless be installed.

Also, the TEXINFOS primary has built-in rules for generating HTML files
from the texinfo sources, so an explicit rule is not needed.

This indirectly addresses https://savannah.gnu.org/bugs/?49969.

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Also: remove the French man pages -- they are too far out of date.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.)

Signed-off-by: Arturo Borrero González <arturo@debian.org>

Also, be more selective when coloring a git diff line.  And color
an svn index line too.

(The variable 'pletion_line' is not conditionalized with this option, as
it would become messy.  The compiler will probably be able to elide it.)

When using --enable-tiny, it is not possible to use --enable-wordcomp,
because the word completion function uses the undo system.

We should avoid defining color schemes that are unreadable on common
white-on-black or black-on-white terminals.  Change the black in the
autoconf error strings to brightred for that reason.

- make version highlight less blindly greedy and conform to real versions
- move version matching before USE matching to avoid hitting USE flags
  that look like versions
- change USE regex to match the Gentoo PMS
- extend arch match to include more keywords
- make category matching more restrictive to avoid false positives
- drop operators =< and => that Gentoo doesn't support

URL: https://savannah.gnu.org/bugs/?49569

Reported-by: Konstantin Shakhnov <kastian@mail.ru>

Also, don't use ignore-case for things that don't contain letters.

Also replace some backslashed spaces because they hinder the
justification of the man page.

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