Some changes to the Vec class and VecTraits in anticipation of creating
Vec-like objects. The following changes are made:
* Add GetNumberOfComponents to Vec, which returns NUM_COMPONENTS.
* Likewise, all VecTraits have a GetNumberOfComponents method.
* The ToVec method in VecTraits is changed to CopyInto so that it can be
used when the length of the Vec-like is not known. CopyInto is also
added to Vec.
* VecTraits has a typedef named IsSizeStatic which is set to
VecTraitsTagSizeStatic when the number of components is known at compile
time and VecTraitsTagSizeVariable when the number of components is not
known until runtime.
C and C++ has a funny feature where operations on small integers (char
and short) actually promote the result to a 32 bit integer. Most often
in our code the result is pushed back to the same type, and picky compilers
can then give a warning about an implicit type conversion (that we
inevitably don't care about). Here are a lot of changes to suppress
the warnings.
On one of my compile platforms, GCC was giving conversion warnings from
any boost include that was not wrapped in pragmas to disable conversion
warnings. To make things easier and more robust, I created a pair of
macros, VTKM_BOOST_PRE_INCLUDE and VTKM_BOOST_POST_INCLUDE, that should
be wrapped around any #include of a boost header file.
