Show approximations for half-life values in the nuclide hover object

[Frencil]

The nuclide hover object is the info box that appears on mouseover for any nuclide. The half-live value shown is always in terms of seconds and this is not that useful outside of a small range of magnitudes.

The Time class does have some documented approximations for orders of magnitude, but only in unit terms (e.g. 1 x 10^n). For familiar time scales within human perception this can't be used directly, so a more sophisticated logic needs to be put together.