TODO: remove 'dispatch-within-dispatch'

it's related to the RPC code, and that's been split out into
protobuf-c-rpc now.
configure.ac: bump version to 1.0.0-rc1
protobuf-c: bump PROTOBUF_C_VERSION to 1.0.0-rc1
README.md: add a "Mailing list" section near the top
README.md: update the synopsis
README.md: update the overview
README.md: link to the protobuf project, not the Protocol Buffers documentation