Merge branch 'refs/heads/t/wma'

A couple of patches which simplify the wma decoder and improve the
robustness of the bitstream API.

Cooking for a month.

* refs/heads/t/wma:
  wma: Remove _XOPEN_SOURCE define from wmadec_filter.c.
  wma: make ->ms_stereo local to wma_decode_block().
  wma: Simplify init_coef_vlc().
  wma: Rename input/output buffer variables.
  wma: Drop unused argument from wma_decode_superframe().
  wma: Remove pointless/incorrect sanity checks.
  wma: Combine wmadec_cleanup() and wmadec_close().
  wma: Simplify get_vlc().
  wma: Remove pointless VLC_TYPE define.
  wma: Make bitstream API more robust.

diff --combined NEWS.md
index 05400a909fa001b10ee63dd7e030648fda4cd3ca,60b942389ffe1a7d71a61ced088965995548d416..5e03421575b5b317595b26223e0f5250aff9aa34
--- 1/NEWS.md
--- 2/NEWS.md
+++ b/NEWS.md
@@@ -1,19 -1,5 +1,20 @@@
  NEWS
  ====
- 
 +---------------------
 +current master branch
 +---------------------
 +
 +- New sort order for the ls command: -s=h sorts the ls output by hash
 +  value of the audio file.
 +- The contents of overview.pdf have been integrated into the user
 +  manual.
 +- The doxygen source browser has been disabled temporarily. The
 +  API reference is still online, though.
 +- Overhaul of the source code documentation.
 +- The deprecated --full-path option of the ls command has been
 +  removed. It was a no-op since 0.6.0.
++- The wma decoder has been cleaned up and its bitstream API made
++  more robust.
  
  -------------------------------
  0.6.0 (2017-04-28) "fuzzy flux"