Idle handling for dpms/lockscreen et al

Swayidle handles idle events and allows
for dpms and lockscreen handling. It also
handles systemd sleep events, and can
raise a lockscreen on sleep

Fixes #541

config.in

@@ -29,6 +29,20 @@ output * bg @datadir@/backgrounds/sway/Sway_Wallpaper_Blue_1920x1080.png fill
 #
 # You can get the names of your outputs by running: swaymsg -t get_outputs
 
+### Idle configuration
+#
+# Example configuration:
+#
+#exec swayidle \
+#    timeout 300 'swaylock -c 000000' \
+#    timeout 600 'swaymsg "output * dpms off"' \
+#       resume 'swaymsg "output * dpms on"' \
+#    before-sleep 'swaylock -c 000000'
+#
+# This will lock your screen after 300 seconds of inactivity, then turn off
+# your displays after another 600 seconds, and turn your screens back on when
+# resumed. It will also lock your screen before your computer goes to sleep.
+
 ### Input configuration
 #
 # Example configuration: