Header option infra + parsing of odd-headlined .org files

This allows following documents to be parsed:

```
#+STARTUP: odd

* level 1
*** level 2
***** level 3
```

NOTE: I was unable to get the tests running under the version of FIVEAM in quicklisp,
so I was unable to run the test suite properly.  Sorry for that..

Besides, are you aware of the formal spec for the Org format by Nicolas Goaziou:

http://article.gmane.org/gmane.emacs.orgmode/67871