Which files in projects are precious?
Most files in build are generated, however, without a build directory, an imported mobile project won't have iphone or android support.
I need to know which files I need to check into my VCS.
This should be a FAQ and should be mentioned in the getting started guide.
You can safely exclude the build folder from your VCS - everything else you will want to add to version control.
Everything within build/iphone/ (And therefor build/android/ etc), unrequired README and LICENSE files.
That's about it.