_ Git - rust-lightning/commit

Remove a handful of redundant imports

... that newer rustc now warns about.

lightning-block-sync/src/init.rs		diff \| blob \| history
lightning-invoice/tests/ser_de.rs		diff \| blob \| history
lightning-net-tokio/src/lib.rs		diff \| blob \| history
lightning-persister/src/fs_store.rs		diff \| blob \| history

Personal fork of Rust-Lightning. Upstream is https://github.com/rust-bitcoin/rust-lightning