Detach the right splos.

Fixes #13.

Conflicts:
	src/Gliph/Graph/AdjacencyList.php
	src/Gliph/Graph/DirectedAdjacencyList.php
	src/Gliph/Graph/UndirectedAdjacencyList.php
	tests/Gliph/Graph/DirectedAdjacencyListTest.php
	tests/Gliph/Graph/UndirectedAdjacencyListTest.php