Pre-B12Digit refactor save

In the process of adding keypad, math, etc., and about to break B12Digit class

B12NumbersV3/MathDisplay.pde

@@ -0,0 +1,16 @@
+class MathDisplay{
+  B12Math math;
+  
+  
+  MathDisplay(B12Math _math){
+    math = _math;
+    digits = new ArrayList<B12Digit>();
+  }
+  
+  // TODO take expression from math and display it in whatever state it is in
+  void display(){
+    for(int i = 0; i < math.expression.size(); i++){
+      
+    }
+  }
+}