LibRaw 0.15 Beta4 changes:

• Fixed possible buffer overrun when RawSpeed library used
• Added new C++ API Call LibRaw::recycle_datastream(), C API call
  libraw_recycle_datastream() and new errorcode LIBRAW_INPUT_CLOSED
  for unpack/unpack_thumb() calls.

  These new API calls may be used to free file handle (and associated
  file buffer) if your application will not call unpack*() on this
  LibRaw handle, so file may be unlocked.

• Support for Imacon Ixpress 39Mpix Multi-shot files