Created LandmarkDatabase
Created LandmarkDatabase

It tracks a whole landmark database as well as a new temporary landmark database.
- Given observations of the form [x1 y1; x2 y2; x3 y3,...xn yn], it does data association, discard useless landmarks (those that are 
   not distinguishable enough) and keep new landmarks separate.
- After we perform EKF update, it provides a function that adds new landmarks to the landmark database and reinitialize the 
   temporary landmark database.
frederikbrinck/slam-gym,frederikbrinck/slam-gym