randomR overflow

[daniel.is.fischer]

When given a large range, randomR overflows at Double etc.

randomIvalDouble has two problems: first, the calculation of the center, (l+h)/2 overflows if the range is located near ±Infinity; second, and that concerns also randomRFloating, the scaling factor (h-l) overflows if the range is large enough.

Both problems can be fixed "well enough" by multiplying the bounds by 0.5 before the calculations and scaling up at the end,

0.5*l + 0.5*h instead of (l+h)/2
(0.5*h - 0.5*l)/(0.5*realToFrac int32Count) in randomIvalDouble
2.0*(0.5*l + coef*(0.5*h - 0.5*l)) in randomRFloating

These transformations can introduce a small error when a subnormal number is involved, but I think we can ignore that (no sane person would have a [nonzero] subnormal number as a bound, and a correct-for-all-cases transformation would be somewhat convoluted).

[rrnewton]

Thanks! Fixes applied. Changes in random version 1.0.1.1.

It looks like there may have been some performance regression; more testing is needed. I don't think it's due to these changes, however. (Though they do add a few extra multiplies.)