Update ne to 3.13

Version 3.13 19-December-2016
-----------------------------

1. Since 3.12 the list of commands that are allowed in readonly mode was out of
step by one.

2. Output "reading" or "writing" when reporting failure to open a file.

3. If a regular expression match in widechars mode encountered a line
containing an invalid UTF-8 string, it behaved as "no match" on that line
instead of reporting the error from PCRE.

4. In screen mode, if a global limit was set, the ending message for a global
match (e.g. "No More: x matches, y changes") was overwritten at the start by a
line number unless "all" was given to the global prompt.

5. The global limit mark has been separated from the text mark and now operates
independently. As a result, it is now possible to cut and paste text and do
bulk line operations while a global limit is set.

6. The "configure" script now checks for the presence of the chosen PCRE
library and also for the termcap or terminfo library.

Version 3.12 04-October-2016
----------------------------

The way that the "back" command works is completely revised. It is now possible
to change the size of the "regions" that "back" remembers, using the BACKREGION
command. The "front" command (defaulted on the ^F keystroke) moves to the line
that is at the top of the back stack.

Version 3.11 19-August-2016
---------------------------

1. NE was crashing if a BACK command was issued before any changes were made
  to the file.

2. "Back" line handling was doing some unnecessary processing and occasionally
  giving a mysterious (incorrect) error message about reading commands in
  binary mode. This should have been "'back' line not found", an internal
  error. The internal error has been fixed. It happened in some cases when two
  changes were made on a line that was subsequently deleted - only one
  instance was removed from the "back" list if the two instances were
  adjacent.

3. "Back" handling wasn't always remembering modification points for certain
    cursor movements.

Version 3.10 27-January-2016
----------------------------

1. Default to using PCRE2, but with a configure option to revert to PCRE1.

2. Removed some old coding macros that were set up for 16-bit Borland C, which
  are surely obsolete now.

3. Fix minor uninitialized read issue in argument decoding on 64-bit systems.

4. After compiling with a lot of warnings enabled, a lot of code tidying has
  been done, mainly turning many int variables into unsigned ints, and
  removing parameters that are not used in Unix-like environments (a hangover
  from early versions that ran on different systems). There is still plenty
  that could be done, however.

5. Removed configure tests for strerror(), memmove(), and bcopy() as these are
  nowadays always available, and anyway, the code no longer checked the
  macros (bcopy() wasn't even used). TIOCGWINSZ was assumed in the
  configuration, so removed the checks in the code.

Version 3.04 27-December-13
---------------------------

1. Change 2 for 3.03 broke full-screen editing when run from a non-xterm
  terminal (e.g. "screen") because it acccidentally insisted on the presence
  of a Delete key.

Version 3.03 09-November-13
---------------------------

1. Removed some set but unused variables (detected by clever new compiler).

2. Updated special keystroke handling for xterm to use more of the default
  strings as specified in the default terminfo file (at least, the one on my
  Arch Linux system).

(prlw1)