* Overhauled real-time notification and chat
    * Much lower server load, especially with multiple tabs
* Improved URL handling (more efficient)
* Improved changelog storage
* Big improvements to the installer
    * Real-time installation status updates
    * No more timeout errors
* Improvements to Relationships for contacts, accounts and opportunities
* Fix for all bugs related to browsers caching old javascript files
* Additional feature in Customization Framework: you can now override controller
  files by adding "My" to the class and putting the file in /custom, for example
  to override actionIndex in ContactsController you can create a class
  MyContactsController extending ContactsController and only define actionIndex.
  This class will automatically be used in place of the original file, and you
  don't have to override the entire class.
* Bug fixes for 2.1.1:
    * Installer: incomplete error reporting
    * Role manager: CSS
    * Updater / updater settings: safeguards & interval setting
    * Mobile (X2Touch) login: JavaScript errors
Note: Any existing changelog data will be preserved, but not visible in the
changelog table. In the next update we will include code to convert this data
to the new format.