IcyDwarf v14.4.1

IcyDwarf: Added gradual dehydration between 700 and 850 K. Basically any
hydrated rocky cell above 700 K starts turning into drier rock and
water. Mass and volume are conserved in that cell by adjusting the
hydration index Xhydr. This is a shaky update, to be further tested.

To do: 
-Add heat of dehydration
-Call the dehydration routine only if rock is not already dehydrated
-Set Xhydr to 0 when it's near 0 within numerical error