There are multiple reasons for this name change:
* The name Tuple conflicts with the boost::Tuple class, which as a
different interface and feature set. This gets confusing, especially
since VTK-m uses boost quite a bit.
* The use of this class is usually (although not always) as a
mathematical vector.
* The vtkm::Scalar and vtkm::Vector* classes are going to go away soon
to better support multiple base data type widths. Having this
abbriviated name will hopefully make the code a bit nicer when these
types have to be explicitly specified.
Also modified the implementation a bit to consolidate some of the code.
In preparation for supporting base types with more widths, add typedefs
for the base types with explicit widths (number of bits).
Also added a IdComponent type that should be used for indices for
components into tuples and vectors. There now should be no reason to use
"int" inside of VTK-m code (especially for indexing). This change cleans
up many of the int types that were used throughout.
