Returns the maximum locally (k,l) connected subgraph of G.
(k,l)-connected subgraphs are presented by Fan Chung and Li in “The Small World Phenomenon in hybrid power law graphs” to appear in “Complex Networks” (Ed. E. Ben-Naim) Lecture Notes in Physics, Springer (2004)
low_memory=True then use a slightly slower, but lower memory version same_as_graph=True then return a tuple with subgraph and pflag for if G is kl-connected