Markdown multilevel lists aren't recognized correctly

[GoogleCodeExporter]

According to Documentation/markdown.md, a second outline level only needs to be 
indented more than the parent level. However, it seems something like the 
following isn't correctly recognized:

-------
* foo
* bar
  * baz
  * quux
-------

Note that only two spaces were used above. Increasing the indent to 4 spaces 
results in correctly recognized sublists.

Original issue reported on code.google.com by asanka@chromium.org on 18 Mar 2015 at 8:47