0.9.3   The R function capture.output(x) does NOT expect a string, therefore we do NOT enclose the parameter in quotes for function MtrDeviceEval0(). For example, capture.output(getwd()) is the correct syntax when used in MtrDeviceEval0().
            When we plot a graph, we do NOT use the function MtrDeviceEval0(), but instead, first we call the function MtrDeviceSinkOn() and followed by MtrRx("plot(x)"). Note that we do NOT need the function MtrDeviceSinkOff() when plotting a graph.