Incorrect parsing of internal RST hyperlink targets

[GoogleCodeExporter]

RST allows "internal" hyperlink targets that refer to the next element.
They can also be "chained."  Pandoc's parser doesn't handle either case
correctly.  See
http://docutils.sourceforge.net/docs/ref/rst/restructuredtext.html#hyperlink-tar
gets

What steps will reproduce the problem?

1. Run pandoc on the following input:

`hello`_

.. _hello:

paragraph

Expected output:  "hello" should link to the paragraph "paragraph", which
should get id="hello".

2.  Run pandoc on the following input:

`hello`_ and `goodbye`_

.. _hello:
.. _goodbye: foo.bar.com

Expected output:  Both "hello" and "goodbye" should be links to foo.bar.com.

Original issue reported on code.google.com by fiddloso...@gmail.com on 12 Feb 2007 at 2:43

[GoogleCodeExporter]

Implementing this would require the ability to put attributes (at least an id) 
on arbitrary block elements.

Original comment by fiddloso...@gmail.com on 23 Jul 2010 at 4:33