title: Best practise to get in sync core code in different projects using git
body: <p>There is a core part in most of the projects I am working on. </p>
  
  <p>Each project is being stored on a separate git repo.<br>
  I want to make a core repository to make all the core changes there and push them to other projects. </p>
  
  <p>I see these ways so far:  </p>
  
  <ul>
  <li>Make one git repo, master for core and branches per project?</li>
  <li>Make one repo for core and somehow push these changes to the others? Parts of the core could be overridden or even deleted.</li>
  </ul>
  
  <p>Please share your thoughts on that subject.</p>