Change the VTKM_CONT_EXPORT to VTKM_CONT. (Likewise for EXEC and
EXEC_CONT.) Remove the inline from these macros so that they can be
applied to everything, including implementations in a library.
Because inline is not declared in these modifies, you have to add the
keyword to functions and methods where the implementation is not inlined
in the class.
This class implicitly stores the point coordinates for a rectilinear
cell (such as a voxel) with just the location of the lower left point
and the spacing in each dimension. In addition to saving space, this
class should allow cell-specific functions to specialize for faster
processing.