native resize for DataBuffer

[Pharmhaus-2]

The native implementation of the DataBuffer currently offers no way to resize the DataBuffer.
Since the _length and the _data fields are private (C++) there is currently no way to interface with C++ code which needs to resize the Buffer. It is also no option to create a new BBDataBuffer because it cannot be passed back to Monkey X without problems. It would be nice if you could implement a native resize method for the DataBuffer.