* landed code for viewing topics in a conference, and for adding a topic

(first workout of HTML Checker code)
* modified the dictionary implementation to use a trie system rather than
  a set of HashSets, and also started using a new, much smaller dictionary
* general bugfixes and cleanup on other items as needed

setup/database.sql

@@ -236,7 +236,7 @@ CREATE TABLE confs (
     nuke_lvl SMALLINT UNSIGNED NOT NULL,
     change_lvl SMALLINT UNSIGNED NOT NULL,
     delete_lvl SMALLINT UNSIGNED NOT NULL,
-    top_topic SMALLINT,
+    top_topic SMALLINT DEFAULT 0,
     name VARCHAR(128) NOT NULL,
     descr VARCHAR(255),
     icon_url VARCHAR(255),
@@ -305,7 +305,7 @@ CREATE TABLE topics (
     confid INT NOT NULL,
     num SMALLINT NOT NULL,
     creator_uid INT NOT NULL,
-    top_message INT,
+    top_message INT DEFAULT 0,
     frozen TINYINT DEFAULT 0,
     archived TINYINT DEFAULT 0,
     createdate DATETIME NOT NULL,
@@ -328,7 +328,7 @@ CREATE TABLE topicsettings (
 # The "header" for a posted message.
 CREATE TABLE posts (
     postid BIGINT NOT NULL PRIMARY KEY AUTO_INCREMENT,
-    parent BIGINT NOT NULL,
+    parent BIGINT NOT NULL DEFAULT 0,
     topicid INT NOT NULL,
     num INT NOT NULL,
     linecount INT,