Merge pull request #6122 from RosettaCommons/roccomoretti/update_rdkit
Update RDKit
Due to interest, update the version of RDKit to 2021.03.5. This version is the same one being used in Foldit (PR #5590) and should be C++14 compatible.
Compilation issues seem to be sorted out if I explicitly ignore some of the new subdirectories in RDKit, which should be okay-ish, as they aren't used elsewhere in RDKit, and aren't used currently by Rosetta. (More extensive fixes may be necessary if we start to use those features.)