add bench target and scripts to run simple benchmark

benches/bench.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+
+cmd=$*
+
+test_html=$(echo "abc" | $cmd | tr -d ' \n')
+[ "$test_html" != "<p>abc</p>" ] && echo "failed simple gen: '$test_html'" && exit 1
+
+for f in *.dj; do
+    tmp=$(mktemp)
+    for i in $(seq 500); do
+        cat "$f" >> $tmp
+    done
+    t=$(cat "$tmp" \
+        | (LANG=C time -p $cmd > /dev/null) 2>&1 \
+        | grep real \
+        | awk '{print $2}')
+    printf "$t\t$f\n"
+    rm -f "$tmp"
+done | sort -rn