Tiny but above subnormal numbers not handled correctly

As mentioned in #119, blocks with all subnormal but nonzero numbers are not encoded correctly because of reciprocal overflow, which can be avoided using the `ZFP_WITH_DAZ` compile-time macro. However, there are even larger, normal numbers that cause problems for zfp due to how they are currently converted to integers here:
https://github.com/LLNL/zfp/blob/c1845815ef1068b578b32823fb22310bd0b62b56/src/template/encodef.c#L42-L59
When the largest (in magnitude) normal value in a block is strictly smaller than 2^-98 ≈ 3.2e-30 for floats or 2^-962 ≈ 2.6e-290 for doubles, overflow in the computation of *s* occurs (even if `ZFP_WITH_DAZ` is enabled). While very small, both of these numbers are well above the smallest normal numbers `FLT_MIN` = 2^-126 and `DBL_MIN` = 2^-1022, respectively.

While less performant, a potential solution is to make use of division by 1 / *s* instead of multiplication by *s* for numbers in this range by computing 1 / *s* via `ldexp` directly, which is guaranteed not to underflow. Note that *s* (and 1 / *s*) is always an integer power of two, so the same result is obtained whether division or multiplication is used (when no overflow occurs). This solution is more general than `ZFP_WITH_DAZ`, as it also correctly handles all-subnormals.

Start by reading src/template/encodef.c at lines 42-59 and the issue's discussion of ZFP_WITH_DAZ and powers-of-two scaling. Investigate the conversion and scaling path for very small normal and all-subnormal values, then verify that those ranges no longer overflow while ordinary values retain the same result.

Written by the indexing model from the issue text.