title: Disable "Add Xtext nature" dialog in Eclipse
body: <p>I'm using a custom DSL with Xtext grammar.
  In my workspace there are several projects, one of them is the development relevant project, another one is for testing purposes.</p>
  
  <p>In the testing project there are a lot (> 5000) of files of my DSL, required for JUnit tests.</p>
  
  <p>When the Xtext nature is added to this project, rebuilding it takes a long time, so I removed it. It's not important to me in the project anyways.
  But now everytime I open one of the files, Xtext asks me to add the nature to this project.</p>
  
  <p>Can I disable this dialog, for a specific project or in general?</p>
  
  <p>Thanks for answers!</p>