NextDenovo2.1-beta.0

1. Fixed a few of bugs.
2. Add a function to del highly repetitive edges.
3. Add an option -G to control whether del potential chimeric edges.
4. Re-construct the function to del low score edges.
5. Increase a better compatibility to run on a slurm system.
6. Add a warning when using the default value of seed_cutoff.
7. Increase more test data to avoid empty results.