added LPCNet torch implementation

dnn/torch/lpcnet/README.md

dnn/torch/lpcnet/add_dataset_config.py

dnn/torch/lpcnet/data/__init__.py

dnn/torch/lpcnet/data/lpcnet_dataset.py

dnn/torch/lpcnet/engine/lpcnet_engine.py

dnn/torch/lpcnet/make_default_setup.py

dnn/torch/lpcnet/make_test_config.py

dnn/torch/lpcnet/models/__init__.py

dnn/torch/lpcnet/models/lpcnet.py

dnn/torch/lpcnet/models/multi_rate_lpcnet.py

dnn/torch/lpcnet/print_lpcnet_complexity.py

dnn/torch/lpcnet/scripts/collect_multi_run_results.py

dnn/torch/lpcnet/scripts/loop_run.sh

dnn/torch/lpcnet/scripts/make_animation.py

dnn/torch/lpcnet/scripts/modify_dataset_target.py

dnn/torch/lpcnet/scripts/multi_run.sh

dnn/torch/lpcnet/scripts/run_inference_test.sh

dnn/torch/lpcnet/scripts/update_checkpoints.py

dnn/torch/lpcnet/scripts/update_output_folder.sh

dnn/torch/lpcnet/scripts/update_setups.py