In this change I:
  Replace the build system for the library with a simplified version that
can be called from modular vtk's build system. For the most part this means
gutting the parts related to wrapping and packaging as vtk's cmake macros
do that.
  Made it so that the vtk directory and libsrc directory are separable so that
once promoted to VTK they can be placed in separate directories.
  Update the style to be more consistent with modern vtk.
  Removed the Ice subdirectory as it appears unused.