MEDIUM / fix EMF add reference bug.
MEDIUM / fix a bug when serializing model uri. The model uri was never
set, thus no resource data could be retrieved when deserializing.
In addition, the type safe model slot instance returned a metamodel
, which should be a model instead. 
Finnaly, just fix a NPE in the edition pattern instance name(in the case
the object is null)
MEDIUM / An exception occurs when the view parameter for serialization
of both virtual model instance model and diagram model is set. I removed
it since it seems not to be used anymore, might I did not understand its
usage...?
MEDIUM / It was not possible to select an object property in the action
add object property statement