…x by re-adding and delegating the old method.

The number of rings can currently calculated by

Cycles.sssr(mol).numberOfCycles();

This is expensive requiring guass matrix elimination. If only the count is needed we can return that much faster. This patch adds the return value to the Cycles.markRingAtomsAndBonds(). You can now do quick filtering like the following:

if (Cycles.markRingAtomsAndBonds(mol) > 0) {
   // has ring
}