v0.5.1

Phylo v0.5.1

Diff since v0.5.0

Merged pull requests:

• Allow export of trees (#88) (@richardreeve)
• Vectors can be AbstractVectors (#89) (@richardreeve)

Closed issues:

• type signatures (#22)
• Test coverage (#50)
• Add function to save/write a tree in Newick format (#61)
• Extraneous linebreaks in show methods (#69)
• parsenexus() tree validation fails if '-' in TaxLabels (#75)
• Tree saving available? (#84)