Using the batch cleanup operation via Source -> Cleanup -> "Use lambdas
where possible" from standard JDT.

Also applied feedback from Karsten Thoms
Manually restored comment in tests/org.eclipse.ui.tests/Eclipse UI
Tests/org/eclipse/ui/tests/decorators/DecoratorTestPart.java which
refactoring deleted

Change-Id: I808b05e3aa9e78d5760897e417aa384ef51fdc67
Signed-off-by: Lars Vogel <Lars.Vogel@vogella.com>