Isotope information ignored for vibrational/thermodynamic quantities

[TyBalduf]

Describe the bug
Isotopic information seems to have no effect on vibrational/thermodynamic quantities. From this commit I had thought isotope information would be incorporated.

To Reproduce
Steps to reproduce the behaviour: (I'm including ethanol as an example, but this has been the case for any molecule I have tried.

1. Run xtb ethanol.sdf --hess -v >> eth_regular.txt (vibrational calculation on regular ethanol)
2. Run xtb ethanol.sdf --hess -v --input temp.txt >> eth_iso.txt (vibrational calculation with all hydrogen mass set to 999.9 in the xcontrol) (isotope xcontrol keyword fails in a similar way)
3. Run xtb eth_iso.sdf --hess -v eth_iso_sdf.txt (vibrational calculation with a specific hydrogen mass set to 999.9 in the sdf

The three calculations give identical output, despite calculation (2) saying that the hydrogen was converted 999.9

Expected behaviour
Some difference between vibrational calculations with isotope information set. I don't know if xTB is supposed to be able to read this information from an sdf, but it seems like it should be able to from the xcontrol input.

Inputs: (Converted sdf to txt to upload)
eth_iso.sdf.txt
ethanol.sdf.txt
temp.txt

Outputs:
eth_iso.txt
eth_iso_sdf.txt
eth_regular.txt