Possible bug in cluster similarity output (-mo option)

[dileep-kishore]

The output of the -mo option always creates a file in which the first two columns and rows are 0.0. You can verify this by trying different combinations of the example .gbk files.

	A. versicolor CBS 583.65	A. mulundensis DSM 5745
A. versicolor CBS 583.65	0.0	0.0
A. mulundensis DSM 5745	0.0	0.0

It is probably happening because of the way distance is calculated here: https://github.com/gamcil/clinker/blob/a9f426be1316c7f8879f56604df42fcc8aedb5cd/clinker/align.py#L598