Wrappers saw GetDataType() method declaration twice.

The wrappers were wrapping the vtkIdTypeArray::GetDataType() method
twice because it appeared both in the macro and again as a straight
declaration.  This resulted in dead code in the python wrappers, I
didn't check Java or Tcl to see how it impacted their wrappers.

Change-Id: Icf71f457e86feb40bb13d1497b458b53a7757bb7
Merge topic 'fix-datatype-bug' into master

bb7932bb Wrappers saw GetDataType() method declaration twice.