Use the strong typed enums for vtkm::cont::Field
Since Field association is used either when creating or working with 'vtkm::cont::Field', it's put in the class itself.
Close #215 (closed).
Edited by Haocheng LIU
Since Field association is used either when creating or working with 'vtkm::cont::Field', it's put in the class itself.
Close #215 (closed).