Isolate new/delete from initial and free.
This should solve the possible memory leak in XnStreamUncompressImageJ().

Now XnStreamCompJPEGContext should use XnStreamCreateCompressImageJ() to create, and then use  XnStreamInitCompressImageJ() to initialize.
To free the resource, should call XnStreamFreeCompressImageJ() first, and then XnStreamReleaseCompressImageJ().
So does XnStreamUncompJPEGContext.