Even if it only allows a range of [1,2], it's there for completeness and makes
the benchmark script a bit easier.

This is currently only implemented for the case where --different-values is
supplied.

When the random experiment says that we should generate non-zero edge, we should
rule out the possibility that this edge gets assigned a random weight of zero.
With small --different-values, zero edges would have become way more likely.

Otherwise states get one of 2^64 different values in the initial partition,
meaning that they will be distinguished already.

This switches from floats to a sort of arbitrary precision base10 floating point
implementation where we can easily generate uniform random numbers.

The problem with floats is that they aren't distributed equally across the whole
range and thus a random number in [0, 1) is not uniform.