Merge branch 'mjcf' into 'Ubuntu18.04'

VirtualRobot/CMakeLists.txt

VirtualRobot/MJCF/Document.cpp

VirtualRobot/MJCF/Document.h

VirtualRobot/MJCF/elements.h

VirtualRobot/MJCF/elements/core/AnyElement.cpp

VirtualRobot/MJCF/elements/core/AnyElement.h

VirtualRobot/MJCF/elements/core/Attribute.cpp

VirtualRobot/MJCF/elements/core/Attribute.h

VirtualRobot/MJCF/elements/core/Element.cpp

VirtualRobot/MJCF/elements/core/Element.h

VirtualRobot/MJCF/elements/core/Visitor.cpp

VirtualRobot/MJCF/elements/core/Visitor.h

VirtualRobot/MJCF/elements/core/const_aware_ptr.hpp

VirtualRobot/MJCF/elements/core/exceptions.cpp

VirtualRobot/MJCF/elements/core/exceptions.h

VirtualRobot/MJCF/elements/core/mjcf_utils.cpp

VirtualRobot/MJCF/elements/core/mjcf_utils.h

VirtualRobot/MJCF/elements/has_member.hpp

VirtualRobot/MJCF/elements/types/actuator.cpp

VirtualRobot/MJCF/elements/types/actuator.h