Refactor source code

[junzengx14]

In the first commit, I moved all files into root folder as we discussed previously that this repo serves for purely python private development.

In the following commits, here are what I plan to carry out: 1) Create a more structured test file for our current need. 2) Add some python checking including pre-commit auto-formatting. and lastly 3) Reorganize current data structure: Add a class for simulation, which contains robot (object), environment (object, contain obstacles). object robot contains objects with controller (object) and planner (object) where we only do function calling inside this class, including dynamics for system dynamics updating.

This allows us to include general dynamics, add other planners while expanding features easily inside controller.

Variables names are not decided yet and we can discuss more once I uploaded more code.

[junzengx14]

For a tiny code display during the early-stage development, I now set black setting with 120 characters length per line. We will move back 88 characters (default for python community) after it's done. I created a CONTRIBUTING.rst to show how to use pre-commit hooks, which allows auto-format at each commit.