Generator class, notebook, mall changes

example/correlation_test.json

example/example_simulation.ipynb

example/frontend_dataset.h5

example/frontend_interface.ipynb

example/pafsim_config.json

pafsim/__init__.py

pafsim/executor.py

pafsim/processor/__init__.py

pafsim/processor/_processor.py

pafsim/processor/channelizer.py

pafsim/processor/correlator.py

pafsim/processor/generator.py

pafsim/receiver/simarray.py

scripts/simulate_dataset.py