read and write phylip files

Specification is here:
http://www.life.umd.edu/labs/delwiche/MSyst/lec/phylip.html

http://www.molecularevolution.org/si/resources/fileformats/phylip_dna.php
http://www.molecularevolution.org/si/resources/fileformats/phylip_protein.php

http://www.ebi.ac.uk/help/formats.html#Phylip

Non interleaved example structure:

<number of seqs> <number of cols>
<10char seq.id><aligned columns>
.
.
. (up to number of seqs)
<next X cols of first sequence>
.
.
.