Merge pull request #2544 from optout21/splicing-msgs0

Add Splicing (and Quiescence) wire message definitions

diff --cc lightning-net-tokio/src/lib.rs
Simple merge

diff --cc lightning/src/events/mod.rs
Simple merge

diff --cc lightning/src/ln/channelmanager.rs
Simple merge

diff --cc lightning/src/ln/peer_handler.rs
Simple merge