wavread is reading too much

[Julien Pommier]

Bug report for Octave 3.0.0 configured for i386-apple-darwin8.9.1

Description:
-----------

wavread does not take into account the chunk size -- if the wav file  
contains other chunks after the data chunk, they are wrongly  
interpreted as audio data

For example, sony sound forge appends such chunks

Fix:
---
"
wavread.m line 153, replace the
     length = Inf
   with
     length = (ck_size * 8)/bits_per_sample;