TODO:

1. Write and use Vector class to store 2 dimensional vectors. Later maybe will be moved to 3 dimensions.

2. Move movement counting code to seperate classes EngineBrute and EngineBarnesHut. Make them return MovementStore object.

3. Write MovementStore class that will be used as maatrix of temporary movement counting, and will be used as bridge between kernels and galaxy.

4. Do the same in c++.