Squirt

This a point release including new features:

• Allow supplementary alignments with --allow-supplementary-alignments flag (resolves #71)
• Patch for guppy connection issues (full fix coming with future Guppy release)
• Better Guppy warnings and help pointers
• Add megalodon_extras calibrate generate_modified_base_stats command
• Lower aggregation batch size default (resolves #76)
  Bug Fixes:
• describe_alphabet error (resolves #87)
• atomize_variants error (resolves #82)