Log Message:
Update ne to 3.18

Version 3.18 04-May-2021
------------------------

1. Allow mark textblock and mark rectangle keystrokes in readonly mode (the
corresponding commands and the "copy" keystroke were already allowed; \ 
this was
an oversight).

2. Two casts in sysunix.c for the 2nd argument of tgetstr().

3. The buffers for file names were too small for very long file names. They
have been increased in size and put on the stack instead of statics in the
binary.

4. Some obsolete memory-handling code has been tidied up. Use size_t for memory
sizes. NE now frees all its memory via an atexit() function, but in screen mode
ncurses doesn't free everything (see various online discussions).

Version 3.17 21-October-2018
----------------------------

1. Added support for Page-up, Page-down, Home, and End keys via terminfo or
termcap.

2. Fix 2 for 3.16 had a bug when the build date was greater than the 9th of the
month.

Version 3.16 07-August-2018
---------------------------

1. In screen mode, if an empty line was given in response to the \ 
"Write" prompt
at the end of editing, NE crashed.

2. Refactor to use memcpy() instead of strncpy() when messing with substrings
in order to avoid GCC string truncation warnings.

3. Implemented the "unformat" command.

4. Allow up to function key 30 (previously was 29, don't know why), and set
function keystring 30 to "unformat".

5. When screen mode was temporarily suspended via the "*" command, if the
"load" or "g" commands required a user response, NE crashed.

6. Recognize -version as well as --version and -v since all other long options
have just a single hyphen.