title: Broken cross-document links with pandoc when converting markdown to other formats
body: <p>Wenn converting markdown files with cross document links to html, docs or pdf the links get broken in the process.
  I use pandoc 1.19.1 and MikTex.
  This is my testcase:</p>
  
  <pre><code>File1: doc1.md
  [link1](/doc2.md)
  File2: doc2.md
  [link2](/doc1.md)
  </code></pre>
  
  <p>The result in html with this call to pandoc:
  pandoc doc1.md doc2.md -o test.html
  looks like this:</p>
  
  <pre><code>&lt;p&gt;&lt;a href="/doc2.md"&gt;link1&lt;/a&gt; &lt;a href="/doc1.md"&gt;link2&lt;/a&gt;&lt;/p&gt;
  </code></pre>
  
  <p>As pdf a link is created but it does not work. Exported as docx it looks the same.</p>
  
  <p>I would have asumed that when multiple files are processed and concatenated into the same output file, then the result should contain page internal links like anchor links for html-output. But instead the link it created in the output file like it was in the input files. Even the original file extension .md is preserved in the created links.
  What am I doing wrong ?</p>
  
  <p>My problem looks a bit like this:
  <a href="https://stackoverflow.com/questions/37327374/pandoc-command-line-parameters-for-resolving-internal-links">pandoc command line parameters for resolving internal links</a>
  In the comments of this question the bug is said to be fixed by a pull request in May. But the bug still seems to exist.
  Greetings
  Georg</p>