Visit parent is now left single click outside context nums on top row.

This is limited to libncurses support of full mouse scrolling.
Ref: https://invisible-island.net/ncurses/man/curs_mouse.3x.html#h3-Mouse-events

incase the user just lost access, it would be better to remember the
selected directory to keep it highlighted.

The previous behaviour would exit nnn when the CWD disappeared.

This reverts commit afdfcecb9c.

These three lines are exact copy of 4555-4557.
As opener is not changed in between, we can delete these

Fixes warning on CentOS 6:

  src/nnn.c:754: warning: ignoring return value of 'fwrite', declared with attribute warn_unused_result

Building on i386 (NetBSD or Debian):

  src/nnn.c: In function 'selectiontofd':
  src/nnn.c:783:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    while (pos <= lastpos) {
               ^
  src/nnn.c:791:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if (pos <= lastpos) {
             ^
  src/nnn.c: In function 'showcplist':
  src/nnn.c:823:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if (pos && pos == copybufpos)
                   ^
  src/nnn.c: In function 'xlink':
  src/nnn.c:1955:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    while (pos < copybufpos) {

The new location is ~/.config/nnn/.lastd

See #187. The behaviour has always remained so confusing. In my case a 0B file
opens in the GUI editor though I have NNN_USE_EDITOR set. We have a sensible
message in place to help users with what to do next.

Author: @bruce-hill