Add sxhkd key bindings file

Added the key bindings from i3 to sxhkd, making use of the new
dmenuprompt program.

.config/sxhkd/sxhkdrc

@@ -0,0 +1,42 @@
+# universal x key bindings
+
+# Open terminal emulator (TODO find way to not hard-code alacritty, perhaps ENV vars)
+mod4 + Return
+  exec alacritty
+
+# open quick start menu
+mod4 + space
+  exec i3-dmenu-desktop
+
+# System functionality
+
+# Enable lock screen (TODO does not stop music, etc yet
+# see https://github.com/LukeSmithxyz/voidrice/blob/archi3/.config/sxhkd/sxhkdrc for that)
+super + x
+  i3lock -e -f -c 1d2021
+
+# Shut down system
+super + shift + x
+  dmenuprompt "SHUT DOWN computer?" "sudo -A shutdown -h now" danger
+
+# Exit X session
+super + BackSpace
+  dmenuprompt "Log out of X Session?" "i3-msg exit" warn
+
+# Restart system
+super + shift + BackSpace
+  dmenuprompt "Reboot computer?" "sudo reboot" danger
+
+# enable function (/media) key functionality
+# TODO: set up next song, previous song, pause, etc
+# see: https://www.reddit.com/r/i3wm/comments/3a6nh3/help_how_to_use_function_keys_in_i3_config/
+XF86MonBrightnessUp
+  exec `xbacklight -inc 10`
+XF86MonBrightnessDown
+  exec `xbacklight -dec 10`
+XF86AudioMute
+  exec `pulsemixer --toggle-mute`
+XF86AudioRaiseVolume
+  exec `pulsemixer --change-volume +5`
+XF86AudioLowerVolume
+  exec `pulsemixer --change-volume -5`