Merged requested to merge ben.boeckel/vtk:vtk-install-tree-fixes into master
ParaView had been relying on these headers being available from the install tree. This worked because they were exported from the library. Now, hide all
vtk_encode_string calls from VTK's libraries except those used by other VTK modules or ParaView. Other classes which had been exported and available anyways are now installed as well.