Merge pull request #845 from ariard/2021-03-hardcode-dust

Switch to a max counterparty's `dust_limit_satoshis` constant

diff --cc fuzz/src/chanmon_consistency.rs
Simple merge

diff --cc fuzz/src/full_stack.rs
Simple merge

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

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

diff --cc lightning/src/util/config.rs
Simple merge