Add benchmarking script.

benchmark.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+BIN="./target/release/indivisible"
+
+if ! [ -f "$BIN" ]
+then
+	>&2 echo "Release build not available. Please run 'cargo build -r'."
+	exit 1
+fi
+
+time "$BIN" 100000000