Merge pull request #4124 from RosettaCommons/roccomoretti/gcc_9.1_fixes
Fixes for GCC 9.1 compilation
Most of the issues with compiling with GCC 9.1 are making sure that the copy constructor and the assignment operator (if both are used) are either both explicit or both implicit. Most changes are mechanical, but there are a few locations where there are copy and assignment discrepancies (or where there were but are no longer.)