Documented missing services in DefaultServiceContainer.cs.
Use DesignSurfaceManager for managing multiple open designers and it provides an implementation of IDesignerEventService. Removed our own DesignerEventService which duplicated what is already there.
Add CodeDomProvider and UndoEngine to the service container as they are requested occasionally by the framework.
Improved disposing of the DesignerViewContent.
git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/trunk@3327 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61