Final Implementation of Version 0.1
Changed mechanism to show regwall from being php based to javascript based. This enables the usage of the plugin with W3TC as regwall display is not determined on client side.
Added Google Analytics tracking. Removed page reload after successful registration (text is now displayed directly by JS).
Make sure regwall js/css are always implanted into code (except for loggedin users) to make sure regwall is shown for w3tc cached pages. Before a race condition was present that caused a non registered user to see the (cached) full page if before a registered user has triggered creation of full page in cache.
Final Changes for GitHub