tNoise now assumes 0.0-1.0 random number input and outputs -1.0 to 1.0

[spiricom]

In our dev code (Matt and I changed this while working on the oversampler). Let's push that change to Master. One thing that is weird about that, though, is that previous code in the Genera and Vocodec set the random number generation function in Main() to generate a -1.0 to 1.0 number, so that tNoise could use it directly. We need to change this in our user code where it occurs. I think this is the right change for LEAF, though.