Previously each device adapter only had a unique string name. This was
not the best when it came to developing data structures to track the status
of a given device at runtime.
This adds in a unique numeric identifier to each device adapter. This will
allow classes to easily create bitmasks / lookup tables for the validity of
devices.
When writing multiple backend code users of vtkm need to use the
DeviceAdapterTraits classes, so therefore we should move them to vtkm::cont
to signify this.
The original isosurface code was not treating the origin and spacing of
the point coordinates correctly. Instead, it was ignoring the origin and
spacing and instead scaling all point coordinates to be in the unit cube
in world space (except there was also an off-by-one error in that). This
change recompensates by adjusting the origin and spacing to make the
correct position where the geometry was previously errantly placed.
This is needed as it allows the policies specified in the root of
vtk-m to propagate properly to the examples. When CMake
sees a cmake_minimum_required command it resets all policy flags.