- avoid code duplication in vtkPV3Foam.C and checkTimeOption.H
  - can also be used in Time::findClosestTime(), but didn't touch that

 - it also found things like size_t instead of size_type in fileName class

 - allows post-processing functions with an optional dictionary
   (eg, the developer can hard-wire some defaults)

We can now add the same member function with different lookups
  e.g. 'stl' and 'stlb'

By using leading/trailing underscores around the lookup name,
we get a unique name and avoid possible collision with other classes.

  This makes it easier to find the usage on the screen.
  Provide hint about -help if the docs cannot be found.