There was an error that caused deprecation warnings in VTK-m to be
suppressed, which meant that many uses of deprecated features went
unnoticed. This fixes those deprecation warnings.
The majority of the warnings were caused by the use of the deprecated
`Cast`, `CopyTo`, and `ResetTypes` methods of `UnknownArrayHandle` (or
`VariantArrayHandle`). Both `Cast` and `CopyTo` have been subsumed by
`AsArrayHandle` (to make the functionality more clear). `ResetTypes` now
requires a second template argument to define the storage types to try.
Also fixed some issues with `SerializableField` being deprecated.
This class is no longer necessary because `Field` can now be directly
serialized.
Updated the image writer classes to better follow VTK-m naming
convention (i.e. use `ImageWriterPNG` instead of `PNGWriter`). The
structure of the image writer class now also better matches the
interface for the VTK writer.
Also put the implementation of the image writers into the `vtkm_io`
library so that it only has to be compiled once.
Updated the image reader classes to better follow VTK-m naming
convention (i.e. use `ImageReaderPNG` instead of `PNGReader`).
The structure of the image reader class now also better matches
the interface for the VTK reader.
Also put the implementation of the image readers into the `vtkm_io`
library so that it only has to be compiled once.