add tracing support to do_biditext16() (convert from XChar2b to char)
biditext plays around with fixed size buffers, not good. 
check for memory leaks

* the printing function of trace prints a non-null terminated string 
  with printf("%s") ?

* Handle Xft's DrawString functions

* Is it good for other bidi. languages as it is? Any charsets need to be
  added?

* [for r2llib] modify r2llib to optionally work with X-windows 
  properties: the "token" should be a property of the top-level window 
  of the application.

  This would allow it to work smoothly with bonobo and kparts programs.

  Problems: 
  - Is it enough to "discover" this window on biditext initialization?
  - use the real top-level window (may be the one of the window
    manager)?
  - What ahppens if the window manager gets shut down?