Deprecate `VirtualObjectHandle` and all other classes that are used to
implement objects with virtual methods in the execution environment.
Additionally, the code is updated so that if the
`VTKm_NO_DEPRECATED_VIRTUAL` flag is set none of the code is compiled at
all. This opens us up to opportunities that do not work with virtual
methods such as backends that do not support virtual methods and dynamic
libraries for CUDA.
There was an error in TestingPointLocatorUniformGrid in which it was
creating arrays of type vtkm::Float32 and passing them to a worklet that
expected vtkm::FloatDefault. This is corrected.
Previously when PointLocatorUniformGrid.h was compiled by the CUDA
compiler, the compiler would crash. Apparently during the ptxas
part of the compiler goes into a crazy recursion and runs out of
stack space. This appears to be a long-standing bug in CUDA
(been there for multiple releases) without a clear reason why it
sometimes rears its ugly head. (See for example
https://devtalk.nvidia.com/default/topic/1028825/cuda-programming-and-performance/-ptxas-died-with-status-0xc00000fd-stack_overflow-/)
The problem appears to be when having a doubly or triply nested
loop over a box of values to check in the uniform array. This
appears to fix the problem by converting that to a single for
loop with some index magic to convert that to 3D indices.
