Setting the number of tuples caused DataChanged() to be called
three times. This patch reduces this to one call.

Further, a RebuildLookup variable is added to vtkDataArrayTemplate that
allows faster calls to DataChanged() that do not require branching.

A style issue is also corrected in SetNumberOfValues.

Change-Id: I5410db9880d9f5c6f9ae2dfb075e81d06f46e275