Add more benchmarks.

benches/engine.rs

@@ -0,0 +1,29 @@
+#![feature(test)]
+
+///! Test evaluating expressions
+extern crate test;
+
+use rhai::{Array, Engine, Map, RegisterFn, INT};
+use test::Bencher;
+
+#[bench]
+fn bench_engine_new(bench: &mut Bencher) {
+    bench.iter(|| Engine::new());
+}
+
+#[bench]
+fn bench_engine_new_raw(bench: &mut Bencher) {
+    bench.iter(|| Engine::new_raw());
+}
+
+#[bench]
+fn bench_engine_register_fn(bench: &mut Bencher) {
+    fn hello(a: INT, b: Array, c: Map) -> bool {
+        true
+    }
+
+    bench.iter(|| {
+        let mut engine = Engine::new();
+        engine.register_fn("hello", hello);
+    });
+}