Performance evaluation

[giafranchini]

We need to perform performance evaluation on the new implemented plugins

• run the state estimator node with perf and analyze results with hotspot
• run the state estimator node with valgrind and analyze results with kcachegrind. Some info here: https://navigation.ros.org/tutorials/docs/get_profile.html

For ceres-related stuff these can be useful:

• http://ceres-solver.org/solving_faqs.html
• https://github.com/ceres-solver/ceres-solver/blob/master/include/ceres/solver.h