new method for message for making KILLED message visible

The cli(); at the start of the kill() function also stops the internal
arduino timer which stops updating of millis() which prevents the
display of the "KILLED." message.
The new function updates the display directly without checking any
timers.

Marlin/Marlin.pde

@@ -1734,7 +1734,7 @@ void kill()
   if(PS_ON_PIN > -1) pinMode(PS_ON_PIN,INPUT);
   SERIAL_ERROR_START;
   SERIAL_ERRORLNPGM(MSG_ERR_KILLED);
-  LCD_MESSAGEPGM(MSG_KILLED);
+  LCD_ALERTMESSAGEPGM(MSG_KILLED);
   suicide();
   while(1); // Wait for reset
 }