Add the possibility to compare different branch far away from each other

[pieer]

Problem

At the moment we can compare only by click on point of contention

Solution

When the user click on the compare button, the circle should have dash line. Then when the user click on one bubble, we have solid line around that circle waiting for the user to click on another bubble to compare. Then a popup appear and show the 2 article information to compare. At the bottom, we should see the button to compare the 2 articles. once this button click we should redirect to the comparison page