* Fixes#1735
I’m unsure if this is the correct solution, it appears
empty molecules never initialize their rings.
* Return immediately when ranking empty molecules
* Make github issue the correct one
* Always resize results to the number of atoms
o rdkit gains a RDKit::common_properties namespace that contains common string value properties
o Dict.h and below gain getPropIfPresent that attempts to retrieve a property and returns
true/false on success or failure. This is used to optimize access.
o rdkit learns how to pass property keys by reference, not value.
A new namespace has been added to RDKit, common_properties
that contains the std::string values for commonly used
properties. This helps to avoid typos in string values
but also avoids a creation of std::strings from character
values. All accessors (has/get/clear and getPropIfPresent) now pass
the key by reference.
Additionally, getPropIfPresent removes the double lookup
of hasProp/getProp which can be a significant speedup
in the smiles and smarts parsers (10-20%)
