samplchallenges/SAMPL7: Version 0.5: Add PHIP2, physical property challenge

This version incorporates diverse changes since the last release, particularly incorporation of the PHIP2 protein-ligand challenge data, and release of the physical property challenge details. These changes include:

• (12/2/2019): Add PHIP2 Stage 2 inputs
• (12/5/2019): Add PHIP2 Stage 2 submission format. Submission link still to come.
• (12/7/2019): Add PHIP2 example submission package.
• (12/7/2019): Add link to bare-bones PHIP2 Stage 2 submission uploads -- open for submissions.
• (12/11/2019): Update PHIP2 stage 2 deadline to noon US Pacific time Dec. 14.
• (12/12/2019): Correct a single exoOA value (for G2) binding, per e-mail from Bruce Gibb.
• (2019-12-14): Add crystal structures of PHIP2 hits, instructions for stage 3.
• (2019-12-20): Add Isaacs' TrimerTrip reference. Add Zenodo DOI for modified cyclodextrin raw experimental data.
• (2019-12-20): Add Stage 2 submissions for PHIP2.
• (2019-12-23): Add Stage 3 submission format for PHIP2.
• (2019-12-23): Add preliminary host-guest analysis (ranked submissions only, for now) for GDCC and TrimerTrip; add preliminary first pass at CD analysis.
• (2020-01-08): Add PHIP2 Stage 3 submission upload.
• (2020-01-14): Include informal reference calculations for trimertrip, GDCC, CD.
• (2020-01-17): Add PHIP2 Stage 3 submissions.
• (2020-02-14): Add additional host-guest analysis/updates to analysis. Include reference calculations in analysis, clean up files.
• (2020-04-10): Add link to host-guest virtual workshop program/video
• (2020-06-29): Add preliminary details of the SAMPL7 physical property challenge on pK_a, log P, and permeability.
• (2020-07-07): Compounds renumbered for the SAMPL7 physical property challenge on pKa, log P, and permeability.
• (2020-08-06): Add physical property submission formats, templates