add RAW /dev/fb0 data screenshots

requires re-encoding or dedicated app to read

README.md

@@ -47,8 +47,9 @@ Remember: all hotkeys will work only in combination with RESET/HOME button (see
 10 = backlight min max  
 11 = remount /mnt as rw  
 12 = remount /mnt as ro  
-13 = screenshot in PNG using fbgrab (slow - more accurate)  
-14 = screenshot in PPM using fbcat (fast - less accurate)  
+13 = screenshot in PNG using fbgrab (slow/accurate)  
+14 = screenshot in PPM using fbcat (fast/less accurate)  
+15 = screenshot in RAW framebuffer data - copy of=/dev/fb0 (fast/accurate)  
 20 = kill, sync and shutdown (quick shutdown)  
 21 = kill gui. Does not work on most apps. do not use  
 22 = kill force app. Work on most apps.  

main.c

@@ -555,6 +555,9 @@ int main(int argc, char** argv)
       case 14:
           system("mkdir -p /mnt/screenshots ; name=/mnt/screenshots/system ; if test -e $name.ppm ; then i=1 ; while test -e $name-$i.ppm ; do i=$((i+1)) ; done; name=\"$name-$i\" ; fi ; fbcat > \"$name\".ppm");
           break;
+      case 15:
+          system("mkdir -p /mnt/screenshots ; name=/mnt/screenshots/system ; if test -e $name.raw ; then i=1 ; while test -e $name-$i.raw ; do i=$((i+1)) ; done; name=\"$name-$i\" ; fi ; dd if=/dev/fb0 of=\"$name\".raw bs=1M");
+          break;
       case 20:
         {
           //printf("quick shutdown\n");