STYLE: Replace vtksys_stl and vtksys_ios:: with std::

In the early days of VTK, support for stl was not portable. vtksys_stl
and vtksys_ios provided a portable implementation of the stl. Now, all
of the VTK supported compilers have portable stl implementations.

This patch:
  1) Replaces the vtksys_ios:: with std::.
  2) Replaces the vtksys_stl:: with std::.
  3) Removes "using" statements for stl