Merge in NetBSD libedit changes and new man pages. Also fix some

Merge in NetBSD libedit changes and new man pages.  Also fix some
strncpy() usage in their code.  NetBSD change log was:
    * add a man page for the editline routines
    * add a man page describing editrc
    * fix bugs in el_parse():
      * didn't execute command when program name matched (test reversed)
      * was checking against empty string instead of program name
      * after checks, command to run also pointed to empty string
    * document ^char and \ escape sequences
    * when parsing ^char control chars, check the correct char when determining
      validity (previously, ^char was a NOP interpreted as the literal string
      because of this bug)
    * Implement CC_REDISPLAY, which (unlike CC_REFRESH) redraws the entire input
    * line (a la ^R). This is useful if the binding outputs information and
    * mucks up the input line. To be used in ``list-choices'' bindings (refer
    * to the ^D binding in csh when filec is set)