Instead of splitting every time scale into two floats, let’s keep only a
single master `whole` number and then a series of fractions, each that
when combined with the whole gives the time in a particular scale. This
saves memory, keeps the attribute list smaller, is conceptually simpler,
and avoids the problem I just encountered with wanting a high precision
two-float version of `ut1` — `ut1_1` or `ut11` would look confusing to
others reading the code, and given that the UT1 timescale at least
includes a number, folks reading `tt1` and `tt2` might have thought
those were different timescales instead of simply two parts of a single
number. So I will be using `whole` and `fraction` consistently in the
code from now on.
1f8e66a42f