Cleared some temporary variables after use

To reduce memory consumption

js/JavaScriptParseTree.js

@@ -29,7 +29,9 @@ var JavaScriptParseTree = function(tree) {
 JavaScriptParseTree.prototype.render = function() {
 	this.output = [];
 	this.renderSubTree(this.tree);
-	return this.output.join("");
+	var r = this.output.join("");
+	this.output = null;
+	return r;
 };
 
 // Render a subtree of the parse tree to an array of fragments of JavaScript source code

js/WikiTextParseTree.js

@@ -61,7 +61,9 @@ WikiTextParseTree.prototype.compile = function(type,treenode) {
 				]
 			}
 		]);
-	return parseTree.render();
+	var r = parseTree.render();
+	this.output = null;
+	return r;
 };
 
 WikiTextParseTree.prototype.pushString = function(s) {

js/WikiTextParser.js

@@ -47,7 +47,10 @@ WikiTextParser.prototype.parse = function(text) {
 	this.dependencies = [];
 	this.output = null;
 	this.subWikify(this.children);
-	return new WikiTextParseTree(this.children,this.dependencies,this.store);
+	var tree = new WikiTextParseTree(this.children,this.dependencies,this.store);
+	this.source = null;
+	this.children = null;
+	return tree;
 };
 
 WikiTextParser.prototype.addDependency = function(dependency) {