[vtkusers] int instead of vtkIdType

[David Doria]

It seems that vtkIdType is the expected type for indices. ie
void GetTupleValue (vtkIdType i, unsigned char *tuple)

I usually do

unsigned char *tuple;

for(int i = 0; i < something; i++
   GetTupleValue (i, tuple);

Is this a bad idea?

Thanks,

David