title: Changing the colour of a calibration plot
body: <p>I've been generating calibration plots for my cph models of survival data. However, the default setting puts the "ideal" line in grey, which makes it difficult to discriminate. I've tried to specify the colour parameters in plot(), but this obviously only changes the line for "observed". What can I pass in plot() to change the line of the "ideal" line in a calibration plot generated in rms?</p>