[phenixbb] "standard" monomer restraints

[Pavel Afonine]

> ideal O3'-C3' bond in *geo is 1.422, which interestingly matches 
> C3*-O3* in `modules/chem_data/geostd/t/data_TD.cif`.

This is expected. I would be worried if they didn't match. So, 1.422 is 
what actually used.

> `elbow.where_is_that_cif_file DT` pointed me to 
> `${CLIB}/data/monomers/d/DT.cif`, where O3'-C3' is (now, but may be 
> not at time of *geo generation) 1.431.

What is ${CLIB} ? I'm wondering because Phenix distribution does not 
have "data/monomers" folders (if I remember correctly).

Pavel