Added new table called "user preferences" which can be used for

storing arbitrary preferences for each user.

Thanks to Jon Papaioannou for the first draft of this code
which I modified.

lib/db/postgres7.sql

@@ -205,6 +205,15 @@ CREATE TABLE prefix_user_admins (
    userid integer NOT NULL default '0'
 );
 
+CREATE TABLE prefix_user_preferences (
+   id SERIAL PRIMARY KEY,
+   userid integer NOT NULL default '0',
+   name varchar(50) NOT NULL default '',
+   value varchar(255) NOT NULL default ''
+);
+
+CREATE INDEX prefix_user_preferences_useridname_idx ON prefix_user_preferences (userid,name);
+
 CREATE TABLE prefix_user_students (
    id SERIAL PRIMARY KEY,
    userid integer NOT NULL default '0',