error in figure 1.

[jeromekelleher]

Recording this so I fix it next time around.

\plr{Whoops! genotype of 1 in the second tree should be `G'!}

[ashander]

Also, to be consistent with listings later in the text (and indeed the way print(ts.dump_tables()) looks the order of child and parent cols in the Edges table should be swapped

[petrelharp]

They all agree now.