fix(boards): 修复arduino下变量名大小写不敏感

boards/default_src/arduino/others/variables.js

@@ -90,7 +90,7 @@ Variables.allVariables = function (root) {
             var varName = blockVariables[y];
             // Variable name may be null if the block is only half-built.
             if (varName) {
-                variableHash[varName.toLowerCase()] = varName;
+                variableHash[varName] = varName;
             }
         }
     }
@@ -222,7 +222,7 @@ Variables.generateUniqueName = function (workspace) {
         while (!newName) {
             var inUse = false;
             for (var i = 0; i < variableList.length; i++) {
-                if (variableList[i].toLowerCase() == potName) {
+                if (variableList[i] == potName) {
                     // This potential name is already used.
                     inUse = true;
                     break;