title: Problems with multiline extension in nxlog
body: <p>I have following logformat:</p>
  
  <pre><code>-- New Entry -------------------------
  08:03:10 01.04.15  ncjhdnbchjbdc
  08:03:10 jnkjsdncksjdnc
  xd1: ndkjewnckjdwcndw
  xd2: jncxkjdsnkjcndsqckjnc c cw djkcdnc cnd kj nc
  08:03:10 dscsdcdsc
  
  -- New Entry -------------------------
  08:03:10 01.04.15  ncjhdnbchjbdc
  08:03:10 jnkjsdncksjdnc
  xd1: ndkjewnckjdwcndw
  xd2: jncxkjdsnkjcndsqckjnc c cw djkcdnc cnd kj nc
  08:03:10 dscsdcdsc
  </code></pre>
  
  <p>I want the complete entry in one line so i use the multiline extension:</p>
  
  <pre><code>&lt;Extension multiline&gt;
      Module  xm_multiline
      HeaderLine  /^--/
      EndLine " "
  &lt;/Extension&gt;
  
  &lt;Input in&gt;
      Module  im_file
      File    "input.txt"
      SavePos TRUE
      ReadFromLast TRUE
      InputType   multiline   
      Exec    if $raw_event !~ /^--/ drop();
      Exec        $raw_event = replace($raw_event, "\r\n", ";");
  &lt;/Input&gt;
  &lt;Output out&gt;
      Module  om_file
      File    "output.txt"
  &lt;/Output&gt;
  
  &lt;Route 1&gt;
      Path    in =&gt; out
  &lt;/Route&gt;
  </code></pre>
  
  <p>The multiline extension works as expected for existing entries in the inputfile after start of nxlog. New entries are not correctly written in the output. Only the header will be written in the output. 
  Has someone an idea of what iam doing wrong?</p>
  
  <p><strong>UPDATE:</strong>
  The PollInterval of the im_file seems to be the problem. I red following in the documentation of nxlog (section xm_multiline):</p>
  
  <blockquote>
    <p>Note Until there is a new header read, the previous message is stored in the buffers because the module does not know where the
    message ends. The im_file module will forcibly flush this buffer after
    the configured PollInterval timeout. If this behaviour is
    unacceptable, consider using some kind of an encapsulation method
    (JSON, XML, RFC5425, etc) or use an end marker with EndLine if
    possible.</p>
  </blockquote>
  
  <p>So, i use an end marker but it doesn't work. I tried different values for EndLine (regex: /^\s*$/ String: " ")</p>