Minor code cleanups
Fix slam_plotter for data sources that contain the entire trajectory, to only show the trajectory up to the current timestep
Improve g2o termination checking
Fix bug in slam_plotter affecting slam_results with non-zero initial states
Revamp code to handle experimental datasets
Keep only the first observation of a feature at any given time step
In mcmc_slam, update parent timestep of feature when new observation is more accurate than the old one
Added non-negative least squares code
Cleaned up Plaza datasets
Added build*/ to .gitignore
Change parent timestep for each landmark to be the one with the smallest range measurement
Minor bugfix
Added (buggy) model-learning code based on non-negative least squares