Fix average local clustering coefficient to be consistent with definition
Fix average local clustering coefficient to be consistent with definition

The previous implementation did not use the definition that was provided
in the comment of the method. The new values will be lower than the old
ones.

fmaschler/networkit,fmaschler/networkit,fmaschler/networkit,fmaschler/networkit,fmaschler/networkit,fmaschler/networkit