background distribution frequencies do not add up to one

[Rohit-Satyam]

Hi I am using your python code to calculate maxZ-Score because this is the only implementation of maxZ paper I got. I am running into this error when I run

maxz -a results/03_nonrefbased/halign3.aln -c no -m binary -d self -s nucleotide
#background distribution frequencies do not add up to one

I have some other nucleotides other than ATGC in my nucleotide MSA which I think the current code does not handle.

PS: I have converted your scripts to make them compatible with Python3. If you plan to upgrade this, I can open a PR. Please let me know.