Add option to start torsiondrive with multiple conformations

[ChayaSt]

Description

Added the ability to start torsiondrive from multiple starting conformations. This can speed up optimization and allows for better sampling of minima.

Todos

Notable points that this PR has either accomplished or will accomplish.

• Add dense omega sampling as conformer generation option.
• Generate an ND grid of initial conformation by driving list of torsions. This allows sampling of some terminal protons that don't get sampled even with omega.SetSampleHydrogens(True)
• Remove conformations that have severe steric clashes.
• Added regression test for workflow API

Questions

• What should be the default setting for the initial conformation grid? Since torsiondrive optimizes all initial conformation and uses the lowest energy of the grid point, there is a tradeoff when starting with too many initial conformations.

Status

• Ready to go

[codecov-io]

Codecov Report

Merging #28 into master will increase coverage by 12.98%.
The diff coverage is 76.08%.

[dgasmith]

Cool! My note of versioning options is that you may want to consider a simple number rather than semantic versioning as that is really specific to code and makes less sense for option versions. Something to think about.