Added the fine grained backlight hierarchy code.

Depending on how the server sets the backlight it controls the clients
(if OPEN then the clients have individual control). If the client is set to
open (inherited from the server) then each screen has backlight control.

server/render.h

@@ -14,8 +14,7 @@
 #define BACKLIGHT_OFF 0
 #define BACKLIGHT_ON 1
 #define BACKLIGHT_OPEN 2
-#define BACKLIGHT_LOAD 3
-#define BACKLIGHT_VIS 4
+#define BACKLIGHT_NOTSET 3
 
 #define BACKLIGHT_BLINK 0x100
 #define BACKLIGHT_FLASH 0x200