"ksdssp is an open source implementation of the algorithm described in Wolfgang
Kabsch and Christian Sander, "Dictionary of Protein Secondary Structure:
Pattern Recognition of Hydrogen-Bonded and Geometrical Features," Biopolymers,
22, 2577-2637 (1983)."

http://www.cgl.ucsf.edu/Overview/software.html

NOTE: the libpdb++ used here is the same as the libpdb in the Reduce
distribution.  Do we need to figure out how to eliminate redundancy?