Misc: Code cleanup

- Form a function ev_window_name() for all window name detection in
  debugging code.

- Add unredir-if-possible to configuration file options.

compton.sample.conf

@@ -39,6 +39,7 @@ vsync = "none";
 dbe = false;
 paint-on-overlay = false;
 sw-opti = false;
+unredir-if-possible = false;
 
 # Window type settings
 wintypes: