Merge branch 'cleanup-querycontext' into 'develop'

CMakeLists.txt

algebra/logical/operators.cpp

algebra/logical/operators.hpp

algebra/physical/Delete.cpp

algebra/physical/Delete.hpp

algebra/physical/GroupBy.cpp

algebra/physical/GroupBy.hpp

algebra/physical/HashJoin.cpp

algebra/physical/HashJoin.hpp

algebra/physical/Insert.cpp

algebra/physical/Insert.hpp

algebra/physical/Operator.cpp

algebra/physical/Operator.hpp

algebra/physical/Print.cpp

algebra/physical/Print.hpp

algebra/physical/Select.cpp

algebra/physical/Select.hpp

algebra/physical/TableScan.cpp

algebra/physical/TableScan.hpp

algebra/physical/TupleStream.cpp