title: svn diff between previous and new working copy
body: <p>suppose that I have made some changes since last update (revert) to my a.b file.
  this a.b file is also changed in the repository.
  Now I want to compare the changes I made with the repos changes.</p>
  
  <p>If I svn revert the file, I can see the changes between new and previous download (previous download doesn't have my changes). How can I see differences between the repository changes and mine?</p>
  
  <p>thanks</p>