Fix Black and White Typo (#2138)

* Fixed typo: Back->Black

* Added Upgrade Rules to fix spelling

* Removed extra isEmpty

* Added previous BackAndWhite to allow for compilation of old scripts

libs/core/enums.d.ts

@@ -416,6 +416,8 @@ declare namespace control {
 
     declare const enum DisplayMode {
     //% block="black and white"
+    BlackAndWhite = 0,  // DISPLAY_MODE_BLACK_AND_WHITE
+    //% blockHidden=true
     BackAndWhite = 0,  // DISPLAY_MODE_BLACK_AND_WHITE
     //% block="greyscale"
     Greyscale = 1,  // DISPLAY_MODE_GREYSCALE