Fixing precision for VTK

src/VTKWriter/VTKWriter_grids_util.hpp

src/VTKWriter/VTKWriter_unit_tests.hpp

test_data/vtk_grids_prp_test.vtk

test_data/vtk_grids_test.vtk

test_data/vtk_points_2d_bin_test.vtp

test_data/vtk_points_2d_pp_bin_test.vtp

test_data/vtk_points_bin_test.vtp

test_data/vtk_points_pp_bin_test.vtp

test_data/vtk_points_pp_header_test.vtk

test_data/vtk_points_pp_header_test.vtp

test_data/vtk_points_pp_test.vtk

test_data/vtk_points_pp_test.vtp

test_data/vtk_points_test.vtk

test_data/vtk_points_test.vtp

test_data/vtk_points_with_prp_names_prec_check_test.vtk

test_data/vtk_points_with_prp_names_prec_check_test.vtp

test_data/vtk_points_with_prp_names_test.vtk

test_data/vtk_points_with_prp_names_test.vtp