#8 OMDataStreamProperty momory leak fix.

[Anonymous]

When we remove a IAAFRIFFChunk, we have to close the stream that belong to the chunk we are removing.
Previously the OMStorable::detach iterated though all the properties and called detach.
However, OMDataStreamProperty, did not overload the detach function, and so the _stream belonging to OMDataStreamProperty was never closed and zeroed out.
That was a memory leak. A virtual detach which closes and clears the _stream has been added to OMDataStreamProperty.

The attached patch file is for the cpp file only, the header file just adds a virtual detatch(void); declaration.

[Nobody/Anonymous]