wavappend

appending to a WAV file is handy when acquiring long streams of data.  my first pass at this (not shown) was to try to add another data block to the riff.  but matlab complained, saying there were no samples in the file.  doing it this way would also require changing wavread to handle multiple data blocks.  from what i understand multiple data blocks are valid, but given these two problems, i instead just lengthened the last/only data block with the new samples.  let me know what you think.