Fix variable increment

Version 0.10.1 fixes a code generation bug when incrementing a variable.

The block "change 'some variable' by..." was generating incorrect, non-compilable code; this version fixes this bug.

Merge pull request #39 from haroldo-ok/fix-variable-increment
This fixes #36

package.json

@@ -1,6 +1,6 @@
 {
   "name": "vcs-game-maker",
-  "version": "0.10.0",
+  "version": "0.10.1",
   "private": true,
   "scripts": {
     "serve": "vue-cli-service serve",

src/generators/bbasic/variables.js

@@ -33,4 +33,13 @@ export default (Blockly) => {
         block.getFieldValue('VAR'), Blockly.VARIABLE_CATEGORY_NAME);
     return varName + ' = ' + argument0 + '\n';
   };
+
+  Blockly.BBasic['math_change'] = function(block) {
+    // Variable increment.
+    const argument0 = Blockly.BBasic.valueToCode(block, 'DELTA',
+        Blockly.BBasic.ORDER_ASSIGNMENT) || '0';
+    const varName = Blockly.BBasic.nameDB_.getName(
+        block.getFieldValue('VAR'), Blockly.VARIABLE_CATEGORY_NAME);
+    return varName + ' = ' + varName + ' + ' + argument0 + '\n';
+  };
 };