Updated the Readme, The test 1D Sod problem with some files (run_tests) to run...

Updated the Readme, The test 1D Sod problem with some files (run_tests) to run the test on diverse mesh sizes by doing e.g ./run_tests Sod B1 from the B1 folder, and a python script to plot B1,B2,B3 on the diverse meshes and for different variables