Merge pull request #6111 from RosettaCommons/LigandDiscoveryMerge Merging in new protocol for motifs-based ligand docking in main/source/src/protocols/motifs/LigandDiscoverySearch.cc. Public app to run the script located in main/source/src/apps/public/motif_ligand_discovery/ligand_discovery_search_protocol.cc. Integration test that uses the app with the protocol found at main/tests/integration/tests/ligand_motif_discovery.