v3.1.4

• added tests for netlist_utils
• fixed crash when creating invalid module when using netlist::create_module
• fixed assigning nets instead of gates when copying netlist using netlist_utils::copy_netlist
• fixed netlist_utils::copy_netlist not copying port names
• fixed netlist_utils::get_subgraph_function crashing on unconnected input pin
• fixed infinite loop within netlist_utils::get_subgraph_function if the combinational logic contains a feedback path