Fix a bug in the rarefaction module.

Now everything is adapt to the environment of Python 3.6. Users of Python 2.7 should have no problem running it. But as a scientist, man, you should use 3.6.

Taxonomy assignment now has been integrated into a single step with filtering and assigning.

You can now find two shell scripts inside the pipeline folder corresponding to ITS1 and ITS2 data.

1. Add an option (-nucl_freq) to get the frequency of nucleotide from either head or tail of all sequences. This is helpful in identifying the highly similar regions (such as SSU, 5.8S, and LSU) before and after fungal ITS.
2. Correct many on screen output errors.
3. Add a function (-filter_taxonomy) to filter taxonomy assignment list based on the match score.
4. Add a function to split taxonomy levels in an OTU table and generate reports.

Fixed some format issues on reading the OTU table.

This is the first release of FAST.