Merge pull request #3906 from RosettaCommons/rhiju/build_a_fold
hotfix to allow loop_close (6D) to be used along with -virtual_anchor_docking in rna_denovo
+ integration tests that change are expected (Due to update of RNA secondary structure) or timeout.
+ one set of unit tests (linux.clang.unit CyclicGeometry...) failed due to timeout on test server; presumably will be rescued upon merge to master as other unit test implementations like linux.gcc.unit worked fine.