Where imol is an integer number
return the specs of the closest atom in imolth molecule
Return a list of (list imol chain-id resno ins-code atom-name alt-conf (list x y z)) for atom that is closest to the screen centre in the given molecule (unlike active-residue, no account is taken of the displayed state of the molecule). If there is no atom, or if imol is not a valid model molecule, return scheme false.