Move benchmarks to an inner crate

That's because there are following requirements:
* Tests should work for pre-1.26 and post-1.26 Rust alike;
* Benchmarks depend on 128-bit integer support from Rand.

The issue is that Rand 0.5 supports that via Cargo feature flag, not
`rustc` version detection and `cfg`-dependent feature selection doesn't
work: <rust-lang/cargo#2524>.

A solution is to have a crate just for benchmarking. The directory
structure looks like this because there are plans to use Criterion for
benchmarking on stable and beta Rusts.

.travis.yml

@@ -43,14 +43,14 @@ matrix:
       script:
         - cargo test --verbose --all --lib --features "nightly test-nightly-regressions"
         - cargo test --verbose --all --tests --features "nightly test-nightly-regressions"
-        - cargo test --verbose --all --benches --features "nightly test-nightly-regressions"
         - which cargo-clippy && cargo clippy --verbose --all --features "nightly test-nightly-regressions"
 
         - cargo test --verbose --all --lib --features "nightly quickcheck test-nightly-regressions"
         - cargo test --verbose --all --tests --features "nightly quickcheck test-nightly-regressions"
-        - cargo test --verbose --all --benches --features "nightly quickcheck test-nightly-regressions"
         - which cargo-clippy && cargo clippy --verbose --all --features "nightly quickcheck test-nightly-regressions"
 
+        - cargo test --verbose --manifest-path bench-suite/Cargo.toml --all --benches
+
         - cargo update -Z minimal-versions
         - cargo build --verbose --manifest-path serde_mtproto_derive/Cargo.toml --lib
         - which cargo-clippy && cargo clippy --verbose --manifest-path serde_mtproto_derive/Cargo.toml

Cargo.toml

@@ -9,6 +9,7 @@ homepage = "https://github.com/hcpl/serde_mtproto"
 documentation = "https://docs.rs/serde_mtproto"
 repository = "https://github.com/hcpl/serde_mtproto"
 keywords = ["serde", "serialization", "telegram"]
+include = ["Cargo.toml", "LICENSE-APACHE", "LICENSE-MIT", "README.md", "src/**/*"]
 
 [badges]
 travis-ci = { repository = "hcpl/serde_mtproto" }
@@ -32,23 +33,17 @@ version_check = "0.1"
 [dev-dependencies]
 derivative = "1.0.2"
 lazy_static = "~1.2"
-lipsum = "0.5"
 maplit = "1.0"
 pretty_assertions = "0.5"
 #quickcheck_derive = "0.2"
 quickcheck_derive = { git = "https://github.com/hcpl/quickcheck_derive", branch = "minimum-supported-rustc" }
+rand = "0.5"
 serde_json = "1.0"
 serde_mtproto_derive = { path = "serde_mtproto_derive", version = "=0.3.1" }  # Update in lockstep
 serde_yaml = "0.8"
 toml = "0.4"
 version-sync = "0.5"
 
-[target.'cfg(stable_i128)'.dev-dependencies]
-rand = { version = "0.5", features = ["i128_support"] }
-
-[target.'cfg(not(stable_i128))'.dev-dependencies]
-rand = "0.5"
-
 [features]
 default = []
 nightly = []

bench-suite/Cargo.toml

@@ -0,0 +1,4 @@
+[workspace]
+members = [
+    "bench-nightly-test",
+]

bench-suite/bench-nightly-test/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "bench-nightly-test"
+version = "0.0.0"
+description = "Benchmark suite using nightly `test::Bencher`"
+authors = ["Nguyen Duc My <hcpl.prog@gmail.com>"]
+license = "MIT OR Apache-2.0"
+publish = false
+
+[dev-dependencies]
+lipsum = "0.5"
+rand = "0.5"
+serde = "1.0"
+serde_derive = "1.0"
+serde_mtproto = { path = "../.." }
+serde_mtproto_derive = { path = "../../serde_mtproto_derive" }

serde_mtproto_derive/Cargo.toml

@@ -3,7 +3,7 @@ name = "serde_mtproto_derive"
 version = "0.3.1"
 description = "Procedural macro helper for serde_mtproto"
 authors = ["Nguyen Duc My <hcpl.prog@gmail.com>"]
-license = "MIT/Apache-2.0"
+license = "MIT OR Apache-2.0"
 homepage = "https://github.com/hcpl/serde_mtproto"
 documentation = "https://docs.rs/serde_mtproto_derive"
 repository = "https://github.com/hcpl/serde_mtproto"