title: How would you go about reverting a single file to previous commit state using git?
body: <p>I wonder why isn't it implemented in the GUI?
  I know git has a content approach vs. single file approach but sometimes single file reverting is crucial.</p>
  
  <p>For instance an .png graphics file from a few commits before is needed.</p>
  
  <p>Probably I need to do a checkout but I'm still not sure as the concepts sometimes escape me.</p>