Refine experimental lifelong mapping to production

[ ] pluginlib objective functions for others to define new and interesting scoring methods that is at the heart of it
[ ] refine objective function to use the number of candidates or graph structure
[ ] necessity to transfer constraints of nodes once decayed -- Additional ideas: before decay check for cycles or that removing it won't fragment the graph, and then transfer the constraints to retain that structure -- Look at optimizer output to see if structure is lost after removal -- See how Ceres scales with Nodes with fixed # constraints, and the constraints with fixed number of nodes -- transfer only some constraints, or only constraints from a loop closure

SteveMacenski / slam_toolbox