How RegisterView is updated.

RemoteTreeViewer is allows deferred updating.
DeferredRegisterGroup is tied to the RemoteTreeViewer.The children of the DefferedRegisterGroup has children IVariable.

The CRegister implements the IVariable, and the interface method getValue() is used to get the value.

Inside the CRegister, there is an internal interface InternalVariable to encapsulate an Register variable.

The getValue() method of InternalVariable will create a shadow variable in the current statck frame, then change to other stack frame. And finally it add the created shadow register to the variable map. At the same time, remove the oldest shadow varaible.