RemoveUnusedPoints contains a couple of worklets and some helper methods
to compact the points in a CellSetExplicit. This is helpful when you
have an operation that creates new cells but might not use all the
original points of the inputs.
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.