Fixed merge conflicts.

b_asic/GUI/drag_button.py

b_asic/GUI/improved_main_window.py

b_asic/GUI/main_window.py

b_asic/GUI/port_button.py

b_asic/GUI/properties_window.py

b_asic/GUI/utils.py

b_asic/core_operations.py

b_asic/graph_component.py

b_asic/operation.py

b_asic/signal_flow_graph.py

test/fixtures/signal_flow_graph.py

test/test_abstract_operation.py

test/test_core_operations.py

test/test_operation.py

test/test_sfg.py