* Made a few additions to the file formats reference.

* Made a few additions to the file formats reference.
* Added two cheats: "mortal" deactivates invincibility, "whereami" prints the player's coordinates to stdout.
* Updated the README.
* Fixed a spelling mistake in Czech translation.
* Fixed a path error in a test level.
* Began converting Bonus Island 2 to the new formats. Extro, worldmap and levelsubset files as well as the first few levels are done. (I wish there was a Lisp parser for Python... or somebody would implement the conversion algorithms into SuperTux itself... until then, it's manual work.)

SVN-Revision: 2868