Revert "refs #10131. Fix doxygen warnings."

This reverts commit adf33460ed0d4900db5f8d6806bbefbbe0e71793.
Revert "refs #10131. Cannot use typename outside of template."

This reverts commit 9e70c2bb468e968e1fb5ccb13d1b1c2bc193b464.
Revert "refs #10131. MultiPeriodWorkspaceAlgorithm refactored."

This reverts commit 62747a94726ff21cfe75e2bf4e9a4a0e732fae24.
Merge branch 'feature/10131_process_groups' into develop