Add benchmarks for message and response creation

As `[bench]` isn't in stable Rust yet, use [Criterion.rs]https://github.com/japaric/criterion.rs)
as the benchmarking harness.

1 files changed, 6 insertions, 0 deletions

diff --git a/Cargo.toml b/Cargo.toml
index c29f852..57bd058 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -21,3 +21,9 @@ fern = "0.4"
 yaml-rust = "0.3.5"
 ctrlc = { version = "3.0", features = ["termination"] }
 
+[dev-dependencies]
+criterion = "0.2.0"
+
+[[bench]]
+name = "messages"
+harness = false