Night Vision - Add scotopic effects to normal vision when dark

[PabstMirror]

As it gets darker human vision switches from cones to rods,
losing the ability to see specific colors ("black and white vision")
as well as having a different luminosity function (rods are much less sensitive to red light)

This uses the new getLighting commands with a color correction to approximate this effect.
It should be somewhat similar to Arma2's night lighting.

Also thanks to dslyecxi for providing the idea for this back when we integrated ST night vision effects

[dslyecxi]

In case you haven't already found this, it's a neat read on this and other vision aspects in low light. You may need to download and open it in Adobe Reader to be able to watch the blue-highlighted sections:
http://graphics.stanford.edu/papers/gazehdr/gazehdr.pdf

[jonpas]

@PabstMirror status on this?

[Mike-MF]

This is actually a really cool feature, I don't know what's left to implement but from testing it I like it. (It has a nice nifty F key toggle atm.)