Added parser rule for HTML format comments

And try it out in the PageTemplate, which is getting pretty
unintelligable

core/modules/parsers/newwikitextparser/rules/comment.js

@@ -0,0 +1,33 @@
+/*\
+title: $:/core/modules/parsers/newwikitextparser/rules/comment.js
+type: application/javascript
+module-type: wikitextrule
+
+Wiki text run rule for HTML comments. For example:
+
+{{{
+<!-- This is a comment -->
+}}}
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+exports.name = "comment";
+
+exports.blockParser = true;
+exports.runParser = true;
+
+// Regexp by Stephen Ostermiller, http://ostermiller.org/findhtmlcomment.html
+
+exports.regExpString = "\\<![ \\r\\n\\t]*(?:--(?:[^\\-]|[\\r\\n]|-[^\\-])*--[ \\r\\n\\t]*)\\>";
+
+exports.parse = function(match,isBlock) {
+	this.pos = match.index + match[0].length;
+	return this.parseBlock();
+};
+
+})();

core/templates/PageTemplate.tid

@@ -1,31 +1,39 @@
 title: $:/templates/PageTemplate
 
+<!-- The navigator catches navigation events and updates the story and history tiddlers -->
 <<navigator story:"$:/StoryTiddlers" history:"$:/History" ><
 
+<!--  Zooming chooser -->
 {{navigation-panel{
 <<chooser><
 	<<list all>>
 >>
 }}}
 
+<!--  Zooming navigator -->
 <<zoomer>>
 
+<!-- The top navigation bar -->
 <div class="navbar navbar-fixed-top">
 <div class="navbar-inner">
 <div class="container">
 {{nav{
 
+<!-- Navigation menu -->
 * HelloThere
 * [[Docs]]
 *{{divider-vertical}}
 
+<!-- View button -->
 <<button popup:ViewDropDownState class:"btn btn-danger"><View <span class="caret"></span>>>
 
+<!-- View dropdown -->
 {{pull-right{
 <<reveal state:[[$:/EditMode]] type:nomatch text:yes><
 <<button modal param:[[$:/messages/EnterEditMode]] set:[[$:/EditMode]] setTo:yes class:"btn btn-success"><Edit>>
 >>
 
+<!-- Save changes is only visible in edit mode -->
 <<reveal state:[[$:/EditMode]] type:match text:yes><
 <<button save-wiki class:"btn pull-right"><Save Changes>>
 >>
@@ -33,6 +41,7 @@ title: $:/templates/PageTemplate
 
 }}}
 
+<!-- This navigator intercepts navigation events and sets the text of the specified tiddler to the target tiddler title -->
 <<navigator set:[[$:/CurrentView]]><
 <<reveal state:ViewDropDownState type:popup position:below><
 <div class="open">
@@ -48,6 +57,7 @@ title: $:/templates/PageTemplate
 </div>
 </div>
 
+<!-- The main story references the same story and history tiddlers as the outer navigator -->
 <div class="container">
 <<story story:"$:/StoryTiddlers" history:"$:/History" storyviewTiddler:[[$:/CurrentView]] storyview:classic >>
 </div>