Free42 possible accuracy flaw

[Thomas Okken]

I'm reluctant to simply remove the repeated-squaring logic. That logic is there for a reason, bid128_pow() is not very good when raising integers to integer powers, and the 2.0u2 revision of the library even includes a patch that does the same thing as the work-around I'm applying to 2.0u1. But it does make sense that bid128_pow() without the work-around works well for (1+1e-8)^1e8, since it does seem to specifically handle bases close to 1. So the question to me is when to use the repeated-squaring work-around and when not to, and that question is relevant to the binary version as well, since the standard library's pow() has the same problem, so there's the question when to use pow() and when to use log1p() and expm1().