Minor fixes:

[JimBayne]

I've been using these 2 fixes since release 1.8. Thought they might be of use.

Fix 1) WaveFileWriter:

• Don't dispose of memory streams in the Finalizer. It deletes them (which defeats WaveFileWriter's purpose)

Fix 2) Mp3FileReader.ReadNextFrame:

• Don't try to read from a closed stream.
• Was happening intermittently in the past (probably due to some sort of timing + multi tasking issue)

Many thanks for this wonderful library.