Hi. I have committed and implementation of the JBIG2 decoder filter.
During the development of this filter I found a problem in the streams code and fixed it: now the semantics of finish_p also apply for reading filters. The consequence is that the encoding filters now also work in reading streams. No modifications are required in the existing filters. The semantics explained in http://www.gnupdf.org/Lib:Architecture/Base_Layer/Stream_Module#Filter_implementations have not changed.
