title: Including multiple classes in the same header file
body: <p>I have an idea on how to do this, but I want to make sure I do it right....</p>
  
  <p>I have five data classes.  When I use one I typically use all of them (but not always).</p>
  
  <p>Each class has a separate header file.  I am getting sick of linking in each header file separately.</p>
  
  <p>What is the best way resolve this issue?</p>