Update TODO.

TODO

@@ -36,6 +36,15 @@ Known bugs
 Missing features
 ----------------
 
+    Add support for storing metadata in .xz files. A preliminary
+    idea is to create a new Stream type for metadata. When both
+    metadata and data are wanted in the same .xz file, two or more
+    Streams would be concatenated.
+
+    The state stored in lzma_stream should be cloneable, which would
+    be mostly useful when using a preset dictionary in LZMA2, but
+    it may have other uses too. Compare to deflateCopy() in zlib.
+
     Support LZMA_FINISH in raw decoder to indicate end of LZMA1 and
     other streams that don't have an end of payload marker.
 
@@ -68,14 +77,35 @@ Missing features
     This is tricky, because the same error codes are used with
     slightly different meanings, and this cannot be fixed anymore.
 
+    Make it possible to adjust LZMA2 options in the middle of a Block
+    so that the encoding speed vs. compression ratio can be optimized
+    when the compressed data is streamed over network.
+
+    Improved BCJ filters. The current filters are small but they aren't
+    so great when compressing binary packages that contain various file
+    types. Specifically, they make things worse if there are static
+    libraries or Linux kernel modules. The filtering could also be
+    more effective (without getting overly complex), for example,
+    streamable variant BCJ2 from 7-Zip could be implemented.
+
+    Filter that autodetects specific data types in the input stream
+    and applies appropriate filters for the corrects parts of the input.
+    Perhaps combine this with the BCJ filter improvement point above.
+
+    Long-range LZ77 method as a separate filter or as a new LZMA2
+    match finder.
+
 
 Documentation
 -------------
 
-    Some tutorial is needed for liblzma. I have planned to write some
-    extremely well commented example programs, which would work as
-    a tutorial. I suppose the Doxygen tags are quite OK as a quick
-    reference once one is familiar with the liblzma API.
+    More tutorial programs are needed for liblzma.
 
     Document the LZMA1 and LZMA2 algorithms.
 
+
+Miscellaneous
+------------
+
+    Try to get the media type for .xz registered at IANA.
+