Enhance logging

[blthayer]

The SAW class creates a logger, but then we never really log anything... We should add a reasonable amount of logging.

[mzy2240]

One idea is to actually parse the log from the simulator, which sometimes could be useful if the function does not have any returns (like most script commands). If someone decide to add this function, please consider to make it modular so that it could also be used as a feedback/confirmation for other functions.