multimedia/nymph*: update to latest RC

There are now RC's for all the parts of nymphcast, update
to those versions. Release notes (although they mostly
point at new binary-builds of the tools) are at

https://github.com/MayaPosch/NymphRPC/releases/tag/v0.1-rc0
https://github.com/MayaPosch/libnymphcast/releases/tag/v0.1-rc0
https://github.com/MayaPosch/NymphCast/releases/tag/v0.1-rc1