Note the PDB ID on error.
Work on issue #81: Made CathDomain implement StructureIdentifier.
Finished SubstructureIdentifier and made Identifier.loadIdentifier
static (as it should have been).
Merge branch 'master' of https://github.com/biojava/biojava
Small improvements and bug fixes for issue #81.
Added guessOrderFromAngle to RotationAxis.
Moved CeSymm and some related classes to biojava-structure.