Add to nimble

[define-private-public]

Hi.

Thanks for you work on this. There do exist some chipmunk bindings on nimble, but those are for 6.x. Can you put this on nimble?

Also, the syntax for the .nimble files has changed. When I do a nimble install from a clone copy of the repo, this shows up. It still install it, but only for now:

   Warning: File inside package 'chipmunk7' is outside of permitted namespace, should be named 'chipmunk7.nim' but was named 'chipmunk.nim' instead. This will be an error in the future.
      Hint: Rename this file to 'chipmunk7.nim', move it into a 'chipmunk7/' subdirectory, or prevent its installation by adding `skipFiles = @["chipmunk.nim"]` to the .nimble file. See https://github.com/nim-lang/nimble#libraries for more info.
  Verifying dependencies for [email protected]
 Installing [email protected]
   Success: chipmunk7 installed successfully.
   Warning: The .nimble file for this project could make use of additional features, if converted into the new NimScript format.
        ... For more details see:https://github.com/nim-lang/nimble#creating-packages