Merging with master

.gitlab-ci.yml

CMakeLists.txt

build.sh

run.sh

src/CMakeLists.txt

src/CSVWriter/CSVWriter.hpp

src/GraphMLWriter/GraphMLWriter.hpp

src/HDF5_wr/HDF5_writer.hpp

src/Plot/GoogleChart.hpp

src/Plot/Plot_unit_tests.hpp

src/VTKWriter/VTKWriter.hpp

src/VTKWriter/VTKWriter_graph.hpp

src/VTKWriter/VTKWriter_grids.hpp

src/VTKWriter/VTKWriter_grids_st.hpp

src/VTKWriter/VTKWriter_grids_util.hpp

src/util/GBoxes.hpp

test_data/gc_num_plot_test.html

test_data/gc_num_ydif_plot_test.html

test_data/gc_out2_test.html

test_data/gc_out3_test.html