New feature: Dual View button for bias control

[Tobi Delbruck]

See https://youtu.be/YI8lWU3jQ_A for a video of the new Dual View button on the jAER User Friendly DVS bias controls. It lets you see how changing the photoreceptor bandwidth, threshold, and refractory period affect the low level DVS pixel bias currents.

For now this feature might only be on the jogl2.5 branch.

Feedback welcome.