And reset the seek position after reading. This new approach where we
also read from empty IBStreams to provide a perfect proxy would
otherwise cause plugins to crash in Bitwig when either loading or saving
state.
This allows presets to contain meta data about file names and the type
of preset.
Even though the docs don't mention that this is also relevant for
`getState()`, we should also implement it there so plugins can write
their own meta data.
Robbert van der Helm