Reverted r5491, r5492, and r5493 as these introduced a bug.
The command used was: svn merge -r5493:5490 .
The problem is that empty MoleculeContainers, ResidueContainers, and SpinContainers should be returned when the selection identifier only selects a higher structure.
Authored by: bugman 2008-04-09
Parent: [r5505]
Child: [r5507]
