Added some comments and ideas to todo.
Modifications in Thing class.

Added:
- Thing can be ghost with no colisions detect
- Added Attack parameter
- Added Radius parameter
- Parameters are set by Thing ID in constructor
- Added some additional logs and comments
Modified World class API

Added:
- AddThing based on thingId and position

Removed:
- grevity from World class
Modified functions in Render class

Added:
- Render uses Thing radius to draw scene
_ Render recognizes Thing type
- Functions for radius access in Thing
Get information about mouse click

Added:
- Added function handling mouseclick
- Parsing information about mouse click in Render