[minor] fix version number on license block comment in common.php

Oops. Forgot to add the themepreview.png file which is a dummy icon for themes that don't include screenshots. Also in last commit several changes weren't documented, including: Moved several page manipulation functions from PageUtils to PageProcess. Fixed debug message in l10n.js. Started switchover to new rollback API and log_id column replacing time_id as key.

Fixed the fact that cron just didn't work at all (brain fart that day or something)

Modifed EnanoMath layer by segregating it into its own file; got support for big_int PHP extension backend working

Fixed improper serializing of IP that could allow reusing of key from multiple IP addresses.

Finished theme manager to the point where it's in a working state in Firefox and hopefully IE.

Documented includes/plugins.php to try and help plugin developers a little.

Fixed some bugs with $paths->getParam() and $paths->get_pageid_from_url() when slashes are in the namespace prefix. Result of testing on Windows Vista + Apache 2.2. Using TortoiseHG

Minor standards-compliance fix in Request_HTTP

Fixed a number of IE6 bugs

Merging in changes from Nighthawk

Upgraded tinyMCE to 3.0.1 in hopes of fixing IE race conditions. Fixed a couple minor syntax errors in Javascript objects declared in various places.

Merging fixes and updates from stable branch

Fixed: RenderMan::getPage() failing with access denial when fetching template and view_source results in deny