* Update libp2p. Add support for ed25519 node (network) keys.
* Update networking to the changes from https://github.com/libp2p/rust-libp2p/pull/972.
* Add support for using ed25519 keys for libp2p networking.
* Add support for reading libp2p secret keys from (external) files.
* Adapt to changes from https://github.com/libp2p/rust-libp2p/pull/992
* More tests.
* Cosmetics
* Deduplicate tests.
* Remove quickcheck from tests that don't use extra random inputs.
* Remove quickcheck.
* Swap new/default impls for NetworkConfiguration.
* Use libp2p-0.5.0 from crates.io.
* Post-rebase update.
* Remove unnecessary wildcard pattern.
* Combine two overlapping tests.
Ensure the config directory exists before trying to write the public key file.
It is the responsibility of obtain_private_key to do so, as per the purpose
of this function.
Roman Borschel