IcyDwarf v14.11.3

Scratch v14.11.2 - differentiation occurs at first melt, i.e. at the
solidus temperature, which is 176 K if there is any NH3 (say >1.0e-5).
v.14.11.1 and earlier were correct.
IcyDwarf v14.12.1

Thermal: decay() now takes into account tzero for long-lived
radionuclides as well. This is useful for simulations of objects that
take a long time to accrete.
IcyDwarf v14.12.1

Thermal: decay() now takes into account tzero for long-lived
radionuclides as well. This is useful for simulations of objects that
take a long time to accrete.