- xml output is a bit wierd -> generate a more generic output
- correct string encoding
- position information of channel in stream: bebob indexes from 1 
  but iec61883 expects it from 0. see todo in avdevice.cpp
- check all std::cout and std:cerr if they couldn't be replaced with 
  the DebugModule's methods. The idea is to have a more consistant
  code.
- All libfreebobavc interfaces should use references instead of pointers
  like in  ExtendedPlugInfoCmd( Ieee1394Service* ieee1394service, ... )
  ->  ExtendedPlugInfoCmd( Ieee1394Service& ieee1394service,
