Add the vtkCriticalTime filter

Given an input that changes over time, the vtkCriticalTime filter generates a new data array containing time step values. These values correspond to the time at which a specified threshold criterion has been met for a given point/cell array (at each point/cell respectively).

To do so, the filter needs to process all available timesteps. The output of the filter in not temporal.

Like in the vtkThreshold filter, the threshold criterion can take three forms:

1. greater than a particular value;

2. less than a particular value;

3. between two values.