change key of NewRowToOldRowsMap to a vtkVariant

This fixes a bug where the wrong rows in the input table could be
used to calculate a value in the output table.

Change-Id: Ibd5dac710f3a8ea1e19971c8fbd13a5742aa86a6
eliminate unused variable warning

Change-Id: I45a40f94ee78f3a696bfebdd66374aa4d4be0dbd
Merge topic 'fix_reduce_table_bug' into master

e86c7af6 eliminate unused variable warning
772916a4 change key of NewRowToOldRowsMap to a vtkVariant
ENH: Update vtkDelaunay2D to support DesiredOutputPrecision

This updates vtkDelaunay2D to support a choice of desired precision
(default, single, or double) for output points. It uses the analogous
code in vtkThreshold as a model.

Change-Id: Ib5d9149f5bb34fc4be0b5005b0e94e38fcf5b52b