Stop displaying machine dependency graph when loading

notebooks/tests/animate.ipynb

notebooks/tests/external_functions.ipynb

notebooks/tests/load_cell.ipynb

notebooks/tests/load_file.ipynb

notebooks/tests/show.ipynb

src/main/java/de/prob2/jupyter/commands/LoadCellCommand.java

src/main/java/de/prob2/jupyter/commands/LoadFileCommand.java