* reference counting on data structures ?
* implement a full featured transaction model - transactions on files
* Thread Save Code?
* open with O_TRUNC ?
* write more the documentation

* implement better error handling (set errno)
* make efstool more comfortable - implement a graphical tool to 
  manipulate efs-files (and show the allocation bitmap)
* more tests for big-endian systems.
  write a better test program (benchmark?) (efstest)