title: How to group columns in React Data Grid?
body: <p>I'm using "React Data Grid" library 
  <a href="http://adazzle.github.io/react-data-grid" rel="noreferrer">http://adazzle.github.io/react-data-grid</a>
  and I want to group columns, and each group should have its own header. </p>
  
  <p>Something like this:</p>
  
  <p>|-------------- Group A header ------------|-------------- Group B header---------------|</p>
  
  <p>|------A1 column-----|-----A2 column----|-----B1 column-----|------B2 column------|</p>
  
  <p>|-------A1 Data-------|------A2 Data-------|-------B1 Data------|-------B2 Data--------|</p>
  
  <p>It should possibly be a not hacky way and all the functions of the library should be still supported (like horizontal scrolling). </p>
  
  <p>I know it's possible to group rows, like this:</p>
  
  <p><a href="http://adazzle.github.io/react-data-grid/examples.html#/grouping" rel="noreferrer">http://adazzle.github.io/react-data-grid/examples.html#/grouping</a></p>
  
  <p>I want the same thing but with columns. Couldn't find it in the docs.</p>
  
  <p>Would be grateful for any tip. Thanks.</p>