title: confusing date manipulations
body: <p>tying to go through all sundays like this:</p>
  
  <pre><code>/*self::WEEK = 604800*/
  /* 3600 * 24 * 7 looks like 7 days for me*/
  
  
      $start = 1286053200;
      for ($i=0; $i &lt; 10; $i++) {
          echo date('d.m.Y H:i:s.u, D (z)', $start) . ' (' . $start . ')&lt;br/&gt;';
          $start += self::WEEK;
      }
  </code></pre>
  
  <p>but in some case i see this:</p>
  
  <pre><code>03.10.2010 00:00:00.000000, Sun (275) (1286053200)
  10.10.2010 00:00:00.000000, Sun (282) (1286658000)
  17.10.2010 00:00:00.000000, Sun (289) (1287262800)
  24.10.2010 00:00:00.000000, Sun (296) (1287867600)
  31.10.2010 00:00:00.000000, Sun (303) (1288472400)
  06.11.2010 23:00:00.000000, Sat (309) (1289077200) &lt;--
  13.11.2010 23:00:00.000000, Sat (316) (1289682000)
  20.11.2010 23:00:00.000000, Sat (323) (1290286800)
  27.11.2010 23:00:00.000000, Sat (330) (1290891600)
  04.12.2010 23:00:00.000000, Sat (337) (1291496400)
  </code></pre>
  
  <p>in other words lost an hour!? where?!</p>