Added support for user, user_roles, page, blog export and import.

Added basic support for comments, for now mainly viewing comments from database (no submission forms yet).
Added first simple wikitext filter (render wikitext content as xhtml).
Ensure response content type is text/html with utf-8 charset.

examples/demo/site/modules/comments/scripts/install.sql

@@ -0,0 +1,13 @@
+CREATE TABLE comments(
+  `cid`	INTEGER NOT NULL PRIMARY KEY AUTO_INCREMENT UNIQUE,
+  `content` TEXT,
+  `format` 	VARCHAR(128),
+  `author`	INTEGER,
+  `author_name`	VARCHAR(255),
+  `created`	DATETIME NOT NULL,
+  `changed`	DATETIME NOT NULL,
+  `status`	INTEGER,
+  `parent` INTEGER,
+  `entity` 	VARCHAR(255),		/* Associated entity */
+  `entity_type`	VARCHAR(255) 	/* Type of associated entity */
+);