Make a new PeerFormats param that can be set on ports to let it know
about the possible peer formats. This can be used by converters to calculate
an optimum conversion.
make the videoadpter query the follower formats, simplify them and then
set them as PeerFormats on the converter.
Implement peerformats in videoconvert. This makes EnumFormat on the port
depend on the negotiated format of the peer. It will suggest a Format
that most closely matches the current negotiated format with the available
PeerFormats. This then makes it possible to negotiate to the format that
would require the least amount of conversions.
