We previously included windows.h in numerous locations using different
techniques to guard against bringing in parts of the file that are bad
(min/max macros, etc). This solves the problem by consistently using
vtkm/internal/Windows.h to setup everything.
Providing these types tends to "lock in" the precision of the algorithms
used in VTK-m. Since we are using templating anyway, our templates
should be generic enough to handle difference precision in the data.
Usually the appropriate type can be determined by the data provided. In
the case where there is no hint on the precision of data to use (for
example, in the code that provides coordinates for uniform data), there
is a vtkm::FloatDefault.
