Split project to different files, and add draw function as a method t…

[tt-abdulhaq]

I did split the project to five files:

• world.rs world struct with its component those we need to create our world.
• physics.rs the functionality we can do on game(world)
• events.rs get user event(user interaction)
• greeting.rs -main.rs and also draw function added as world struct method.

[jadijadi]

Thank you very much. Very clean and useful for the project.