buttons semi-functional

src/main/java/rocks/zipcode/calcskin/CalcSkin.java

@@ -24,7 +24,7 @@ public class CalcSkin extends Application {
         launch(args);
     }
     private static final String[][] template = {
-            { "7", "8", "9", "/", "sqr" },
+            { "7", "8", "9", "/", "sqR" },
             { "4", "5", "6", "*", "sqRt" },
             { "1", "2", "3", "-", "exp" },
             { "0", "c", "=", "+", "inv" }