Adding new contaminant screening feature

• Adding 'separately' contamination screen option.

0.2.3

• Includes Singletons in Network Summary

0.2.0

• Updates hivtrace to use BioExt >= 0.18.0 in order to use bealign's updated penalty scoring when aligning to a reference.
• Updates LANL sequence alignments and TN93 results based on bealign's updated penalty scoring