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.
Based on the work of Tyson Neuroth and Huu Tan Nguyen at the VTK-m code
sprint.
Shows how to invoke a simple worklet to generate coordinates and colors,
and than use opengl interop to display it to the screen.
