[sxhkd] Add sxhkdrc parsing to mode script

Can now parse the usual sxhkdrc file in looking for mode chain
combinations. Will prefer explicit configuration files if they exist.
Read the -h to learn more.

sxhkd/.config/sxhkd/chain-labels.example.conf

@@ -1,7 +1,7 @@
 # for sxhkd-chain-labels script
 
 # media manipulation mode: playing, pausing, skipping,..
-media:super + alt + m
+media:alt + m
 
 # academia mode: opening bibtex readings, annotating,..
-academia:super + alt + a
+academia:alt + a

sxhkd/.config/sxhkd/sxhkdrc

@@ -44,7 +44,7 @@ super + q
 
 ## modes
 
-# media control mode
+# mode:media:alt + m
 # seek +/- 5 seconds
 alt + m : {h,l}
   playerctl position {5-,5+}
@@ -61,7 +61,7 @@ alt + m : shift + {j,k}
 alt + m : {_,shift} + p
   playerctl {play-pause,stop}
 
-# academia mode
+# mode:academia:alt + a
 # due papers this week
 alt + a : {F1,F2}
   rofi-bib-due -p{1,3} -u $(date --date='fri this week' +%Y-%m-%d)