[db] Block neighbors no longer cache values - dynamically calculated now
[db] all objects in SpacerContainer now have _release() methods
[db] moves ros system graph updating functionality direclty into the RSG
[db] this just got moved into ros_topology, saved here for now
[db] fixes to getting rid of objects in qtview
[db] saved state
[db] updates the rostest program
[db] DrawingBoard refactored to be known as TopologyWidget
[db] ros_diarc now uses TopologyWidget too!
[db] seperates the notion of the RosSystemGraph and the
LiveRosSystemGraph