Release version 0.2.0

Release version 0.2.0

### Added
- Compilation macros that can specify output binary parameters.
- Auxiliary build and test scripts.
- Nearest neighbour `nn2` procedure based on linear search over `nodes()`.
- Nearest neighbour `nn3` procedure based on indexing over `y` axis.
- Near vertices `nv2` procedure based on indexing over `y` axis.
- OpenMP parallelization of nearest neighbour and near vertices procedures.
- Rebase method that changes (rebases) RRT root to another RRT node.
- Structure and method for logging tree edges.
- Time dimension to RRT node.
- Obstacle distance to RRT Node.
- Test planner `T2` based on RRT\* [Karaman2011] with steering from newly added
  nodes to goal.
- OpenGL 2.1 plot using SDL2.
- `nn4` procedure - set node's heading to heading of currently comparing node.
- Add optimize path method based on [Islam2012]'s *Path Optimize* procedure.
- Update cost method of `RRTNode` that updates cumulative costs of all
  children.

### Changed
- Build with Ninja.
- Split `connect` and `rewire` procedures from Karaman2011's `next` procedure.
- Main planning loop logic.
- Path optimization of `T2` based on Dijkstra between cusps points.

### Fixed
- Deletion of nodes returned by `steer` but not used.
- Scaling for `iy_` nearest neighbour search structure.