[SDL] Gamma control with DirectColor visuals (fwd)

[Sam Lantinga]

> >The above function is only part of a test program. SDL itself doesn't
> >make any assumptions about gamma. You simply feed it with a gamma ramp
> >:-)

> I thought Sam intended to include SDL_SetGamma() as well as SetGammaRamp().
> There could be hardware you cannot control with a ramp but whose gamma
> is settable from a scalar. You could integrate the ramp but that
> gets too slow and messy

No, I planned to support one or the other.  There is so little real gamma
support out there, that I'd hate to provide two useless functions. :)

See ya!
	-Sam Lantinga, Lead Programmer, Loki Entertainment Software