* tests needed:
  - gstreamer (testcase file exists, but does not test everything important)

Desirable missing formats:
* mbox / various e-mail formats
* info pages (scan for 'Node: %s^?ID' - see end of .info files!)
* sources (Java, C, C++, see doxygen!)
* a.out (== ar?)
* rtf
* applefile (0.6.x-plugin exists)
* EXE
* ELF (linkage information, 0.6.x-plugin exists)
* PRC (Palm module, http://web.mit.edu/tytso/www/pilot/prc-format.html)
* KOffice
* TGA
* Microsoft OOXML (MS Office >= 2007)