merged w/ latest develop

b_asic/__init__.py

b_asic/abstract_graph_component.py

b_asic/abstract_operation.py

b_asic/core_operations.py

b_asic/graph_component.py

b_asic/operation.py

b_asic/port.py

b_asic/signal.py

b_asic/signal_flow_graph.py

test/signal_flow_graph/test_signal_flow_graph.py