First working JFace example

[Frank Benoit]

Now the JFace stuff compiles with the available dwt on win/linux.

dwt-samples/jface/ActionAndStatusbar
is a first showcase.


More example code as showcases and testcases is very welcome.
Snippets can be found here:
http://wiki.eclipse.org/index.php/JFaceSnippets


Due to a compiler bug (#1978), the tango collection need a fix to make 
JFace not going into a endless loop.

- tango.util.collection.mode.View
   line 39  : public Dispenser!(T) duplicate();
   change to: public View!(T) duplicate();


- tango.util.collection.mode.Set
   line 37 add:
   public Set!(T) duplicate();
   public alias duplicat dup;