During the VTK-m 1.8 and 1.9 development, the filter infrastructure was
overhauled. Part of this created a completely new set of base classes. To
avoid confusion with the original filter base classes and ease transition,
the new filter base classes were named `NewFilter*`. Eventually after all
filters were transitioned, the old filter base classes were deprecated.
With the release of VTK-m 2.0, the old filter base classes are removed. The
"new" filter base classes are no longer new. Thus, they have been renamed
simply `Filter` (and `FilterField`).
Previously, `DataSet` managed `CoordinateSystem`s separately from `Field`s.
However, a `CoordinateSystem` is really just a `Field` with some special
attributes. Thus, coordiante systems are now just listed along with the
rest of the fields, and the coordinate systems are simply strings that
point back to the appropriate field. (This was actually the original
concept for `DataSet`, but the coordinate systems were separated from
fields for some now obsolete reasons.)
While updating the slides for an upcoming tutorial, some minor changes
were made to the tutorial examples to more clearly explain concepts or
simply fit things better on slides.
