BUG: Dynamic zero divide errors
vtkChartBox: replaced a retained, returned pointer with a stored value.
vtkChartXY: Added check for range[0] == range[1] and avoid division by zero.
vtkFunctionParser: Added check for division of a vector by 0.0.
vtkUnstructuredGridQuadricDecimation: first time through loop, lasterror is 0.0. Avoid division by zero by checking for 0.0.
Edited by Bill Lorensen