title: Original domain in periodic triangulation with CGAL
body: <p>I have some questions regarding the periodic triangulation in CGAL.</p>
  
  <p>1) According to my understanding of the manual examples (<a href="http://doc.cgal.org/latest/Periodic_2_triangulation_2/examples.html" rel="nofollow">http://doc.cgal.org/latest/Periodic_2_triangulation_2/examples.html</a>) and the <em>reference manual</em> if we don't use Iso_rectangle in constructing triangles, (0,0,1,1) is chosen as the default value, am I right?</p>
  
  <p>2) What is the meaning of this statement from manual? "<em>input point is required to be an element of the half-open square representing the original domain</em>"</p>
  
  <p>3) "<em>Another effect is that when the algorithm switches from 9-sheeted covering to 1-sheeted covering the Vertex_handles and Face_handles referencing deleted items becomes invalid</em>", Does this mean that If I have vertex circulator in code, those adjacent vertices that are in periodic boxes, are neglected and not displayed in the output?</p>