Add blur and make dotfiles more flexible

Add blur using the fork from https://github.com/tryone144/compton.
picom seems to be very CPU heavy on my system, so until I figure out how
to fix that I will use this outdated version.
Make the dotfiles a bit more flexible by creating symlinks for stuff
like the wallpaper or the compositor. When switching/exchanging these
components only the symlinks have to be updated.

.config/xsecurelock/transfer-sleep-lock.sh

@@ -20,14 +20,14 @@ sleep_delay=1
 # Run before starting the locker
 pre_lock() {
     playerctl pause
-    killall -q compton
+    "${XDG_CONFIG_HOME:-$HOME/.config}/compositor/launch.sh" -k
     amixer -q -D pulse sset Master mute
     return
 }
 
 # Run after the locker exits
 post_lock() {
-    compton -b
+    "${XDG_CONFIG_HOME:-$HOME/.config}/compositor/launch.sh"
     return
 }