v0.1.9: Parallize var_inf, improve docstrings and add bpz file download

What's Changed

• 46 parallelize var inf by @joselotl in #77
• Creation docstrings by @OliviaLynn in #78
• Add bpz files; reduce duplicated logic in if/else by @OliviaLynn in #76

Full Changelog: v0.1.8...v0.1.9