Marbles: LEDs only show positive values

[mhetrick]

On the Marbles emulation, the CV and Y LEDs are only displaying green/positive voltages. On my factory hardware modules, the LEDs also turn red to display negative voltages.

Additionally, the LEDs seem to be too sensitive, like they're peaking out too early. On the hardware it seems like the LEDs have more of a "range". Are the voltages being downscaled correctly (i.e. from -5/5 to -1/1)?