DNA/RNA ribbons are now available through the function
OEMakeProteinRibbonSurface. When molecules containing
DNA or RNA residues are passed to this function with a ribbon style of
OERibbonType_Pretty, the resulting surface will
contain ribbons for both protein and nucleic acid residues.
OEMakeAccessibleSurface no longer crashes when passed
extremely large molecules (many hundreds of Angstroms across). The function
now reduces the resolution of the surface, if necessary, to allow the surface
to fit in the available memory.