Add benchmark test

tests/bench/benchmark.spec.js

@@ -0,0 +1,45 @@
+import Engine from '../../src/Engine';
+import Component from '../../src/Component';
+
+describe('benchmark', () => {
+    let engine, query;
+
+    class ComponentA extends Component {}
+    class ComponentB extends Component {}
+
+    it('does 10000 additions and removals', () => {
+        let time = 0;
+        const testCount = 10;
+
+        for (let i = 0; i < testCount; i++) {
+            engine = new Engine();
+
+            engine.registerComponent(ComponentA);
+            engine.registerComponent(ComponentB);
+
+            query = engine.createQuery({
+                all: [ComponentA, ComponentB]
+            });
+
+            const start = Date.now();
+
+            for (let j = 0; j < 10000; j++) {
+                const entity = engine.createEntity();
+
+                entity.add(ComponentA);
+                entity.add(ComponentB);
+            }
+
+            const end = Date.now();
+            const delta = end - start;
+
+            console.log(`T${i} ${delta}ms`);
+
+            time += delta;
+        }
+
+        const avg = time / testCount;
+
+        console.log(`AVG ${avg.toFixed(2)}ms`);
+    });
+});