Fix indeterminant linear system

[koide3]

• Fix the graph when an indeterminant linear system is detected by inserting a damping factor and resetting the smoother.
• Add a few optimization tools to the standard viewer.

[changh95]

Just tested this code - it works nicely.

I tested this code on a rosbag with some corruption when global_mapping_gpu is on. The indeterminant linear system exception arised due to corruption in dataset. Prior to this code change, the system crashed soon after. But with this code change, the isam2 resets and lets the system keep going. Despite a number of times this exception appeared, GLIM managed to terminate safely.