Ir-sim

- Rename the module name from ir_sim to irsim, rename the package name from ir_sim to ir-sim
- Add citation for the project
- Refine the comments for the functions
- Configure the readthedoc and sphnix for documentation
- Add the attribute unobstructed for obejcts, see usage: obstace_world for detail
- Fix the state_dim bug

- Rename the module from ir_sim to irsim, rename the package name from ir_sim to ir-sim
- Add citation for the project
- Refine the comments for the functions

- Update function comments
- Update the readme
- Add interface to change the object distribution in the environment
- Add Feature of obstacles random in the environment

- Fix errors in usages
- delete some old files
- Fix some bugs

- Fix bug for omni dynamics robots
- Fix bug for rvo behavior
- Replace the diff description for the object_base

- Update the YAML API
- Enhance features in object_base (G, h)
- Expand project development utilities
- Fix some bugs