API: added from_file
TST: symmetric test on RFD
DOC: raises section added to shear
TST: added additional test on accumulate_to_ancestor
TST: make sure from_newick can handle list
ENH/TST: LCA raises when no tips are found
TST: test for TreeNode.levelorder
TST: pre_and_postorder traversal test
TST: test for tips()
TST: test for remove_deleted
TST: test for __iter__