title: Android reuse activity from activity stack and clear it
body: <p>I have application with main activity and some more.
  On each other activity there is the logo of the application.
  When user presses the logo button, I want to get back to the main activity.</p>
  
  <p>I do not want to create new intent, since activity aready on the activity stack.</p>
  
  <p>How can I get it - use the one on the stack?
  How can I clear the whole activity stack, so back button will actually exit from the application instead of getting back to the previous activity?</p>
  
  <p>Yoav</p>