This PR addresses issue #1095, where some arguments to nyquist_plot were not being processed correctly. The issue was that not all arguments to nyquist_plot that needed to be passed through for processing in nyquist_response were listed. The fix was to pass a dictionary of keywords to nyquist_response in a way that it could pop elements off of the dictionary that it processed, leaving only those that nyquist_plot needs to handle.

I also added some unit tests that expose this bug and also check to make sure that all of other relevant response/plot function pairs pass on arguments correctly.