graph/simple: node ID addition is slow
Created by: kortschak
See discussion at https://groups.google.com/d/topic/gonum-dev/twUcG1rEMIU/discussion
Also note that this impacts on decisions regarding the integer type used for node IDs in #31.
Created by: kortschak
See discussion at https://groups.google.com/d/topic/gonum-dev/twUcG1rEMIU/discussion
Also note that this impacts on decisions regarding the integer type used for node IDs in #31.