Use synchronous file writes for saving tiddlers

So that we don't get problems with "docs.tid" overwrites "Docs.tid"
halfway through each other

core/modules/commands/savetiddlers.js

@@ -42,9 +42,7 @@ Command.prototype.execute = function() {
 		var renderTree = new $tw.WikiRenderTree(parser,{wiki: wiki});
 		renderTree.execute({tiddlerTitle: title});
 		var text = renderTree.render(type);
-		fs.writeFile(path.resolve(pathname,title + extension),text,"utf8",function(err) {
-			self.callback(err);
-		});
+		fs.writeFileSync(path.resolve(pathname,title + extension),text,"utf8");
 	});
 	return null;
 };