Update "examples/find-lowres"

Closes #463

Closes #456

Otherwise, several --info switches will not properly override each other

This fixes "feh -D -1 -D 1" and similar starting the slideshow in paused mode
even though the last -D option specifies autostart.

Closes #456

Note that --randomize and directory names are not saved in fehbg. It only
contains the command line needed to recreate the wallpaper setup which
resulted from its invocation, i.e., after randomization etc. have been
applied. This is intentional.

closes #458

Update "src/signals.h"

Update "share/applications/feh.pre"

Update "man/feh.pre"

Use "extern volatile" instead of "volatile extern" to avoid "gcc" warning "'extern' is not at beginning of declaration [-Wold-style-declaration]".

Convert "examples/find-lowres" from "zsh" script to "sh" script.

Small fixes in man page.

There is no need to test ft against null

ft is already checked on line 153 so this condition is useless. Check https://github.com/derf/feh/issues/440 for more details

It is a naive way of fixing it :) Needs attentive review

sig_exit may be changed by a signal handler, so its value should always be
read from RAM.

See also #435