Docs: Update TODO a little

TODO

@@ -5,12 +5,7 @@ XZ Utils To-Do List
 Known bugs
 ----------
 
-    The test suite is too incomplete.
-
-    If the memory usage limit is less than about 13 MiB, xz is unable to
-    automatically scale down the compression settings enough even though
-    it would be  possible by switching from BT2/BT3/BT4 match finder to
-    HC3/HC4.
+    The test suite is incomplete.
 
     XZ Utils compress some files significantly worse than LZMA Utils.
     This is due to faster compression presets used by XZ Utils, and
@@ -38,9 +33,6 @@ Missing features
     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.
-
     Adjust dictionary size when the input file size is known.
     Maybe do this only if an option is given.
 
@@ -64,9 +56,9 @@ Missing features
     Support LZMA_FULL_FLUSH for lzma_stream_decoder() to stop at
     Block and Stream boundaries.
 
-    lzma_strerror() to convert lzma_ret to human readable form?
-    This is tricky, because the same error codes are used with
-    slightly different meanings, and this cannot be fixed anymore.
+    Error codes from lzma_code() aren't very specific. A more detailed
+    error message (string) could be provided too. It could be returned
+    by a new function or use a currently-reserved member of lzma_stream.
 
     Make it possible to adjust LZMA2 options in the middle of a Block
     so that the encoding speed vs. compression ratio can be optimized
@@ -94,9 +86,3 @@ Documentation
 
     Document the LZMA1 and LZMA2 algorithms.
 
-
-Miscellaneous
-------------
-
-    Try to get the media type for .xz registered at IANA.
-