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.
The Transport class is responsible for moving data from the control
environment to the execution environment. (Actually, it might be more
accurate to say it gets the execution environment associated with a
given control object.) The Transport class is templated with a tag that
controls the mechanism used for the transport.
