Allow users to set the range of values for the scales curve displays (ECG and pulse)

[sabinammm]

Allowing an individualized display of curve value ranges can be helpful for diagnostic purposes. For example, it may be helpful to confine the range of values in an ECG (zoom-in effect) so that less ECG cycles are depicted at a higher resolution. This will allow users to localize anomalies more easily and to determine the causes of these. If, however, the ECG is only needed to monitor a patient, the display of many ECG cycles at a lesser resolution will make more sense.