Bug 448143 - CellModifier API should be removed from Platform code

Change-Id: I16d8e3aeb4911e7050749b47269b3bf44607396c
Signed-off-by: Simon Scholz <simon.scholz@vogella.com>
Bug 446233 - Remove org.eclipse.e4.ui.internal.workbench.ExitHandler,
class also available in handlers package 

Change-Id: I4dc9908485f6ae8b9778a8fa675fc1b9ae4e6819
Signed-off-by: Lars Vogel <Lars.Vogel@vogella.com>