Add help command

core/modules/commands/help.js

@@ -0,0 +1,41 @@
+/*\
+title: $:/core/modules/commands/help.js
+type: application/javascript
+module-type: command
+
+Help command
+
+\*/
+(function(){
+
+/*jshint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+exports.info = {
+	name: "help",
+	synchronous: true
+};
+
+var Command = function(params,commander) {
+	this.params = params;
+	this.commander = commander;
+};
+
+Command.prototype.execute = function() {
+	var subhelp = this.params[0] || "default",
+		helpBase = "$:/language/Help/",
+		text;
+	if(!this.commander.wiki.getTiddler(helpBase + subhelp)) {
+		subhelp = "notfound";
+	}
+	// Wikify the help as formatted text (ie block elements generate newlines)
+	text = this.commander.wiki.renderTiddler("text/plain-formatted",helpBase + subhelp);
+	// Remove any leading linebreaks
+	text = text.replace(/^(\r?\n)*/g,"");
+	this.commander.streams.output.write(text);
+};
+
+exports.Command = Command;
+
+})();