Virtual methods are being deprecated, so remove their use from the
ColorTable classes. Instead of using a virtual method to look up a value
in the ColorTable, we essentially use a switch statement. This change
also simplified the code quite a bit.
The execution object used to use pointers to handle the virtual objects.
That is no longer necessary, so a simple `vtkm::exec::ColorTable` is
returned for execution objects. (Note that this `ColorTable` contains
pointers that are specific for the particular device.) This is a non-
backward compabible change. However, the only place (outside of the
`ColorTable` implementation itself) was a single worklet for converting
scalars to colors (`vtkm::worklet::colorconversion::TransferFunction`).
This is unlikely to affect anyone.
I also "fixed" some names in enum structs. There has been some
inconsistencies in VTK-m on whether items in an enum struct are
capitolized or camel case. We seem to moving toward camel case, so
deprecate some old names.
The problem is that there is no good "default" constructor for
ColorTable. The previous default constructor created an empty color
table, but that would be confusing if someone actually tried to use it.
We could set ot to the default preset, but the default preset uses the
diverging color map, which could foul people up if they actually want to
edit or create their own color map. Instead, force the declaration of
ColorTable to indicate what you plan to do with it.
Sandia National Laboratories recently changed management from the
Sandia Corporation to the National Technology & Engineering Solutions
of Sandia, LLC (NTESS). The copyright statements need to be updated
accordingly.
The clang compiler was running into linker errors constructors of
classes with virtual methods that were inline and destructors that were
not declared at all. In this case, the compiler was not creating
everything needed by a virtual table and the link died.
