Add a testcase for codeblocks

tests/code.t

@@ -0,0 +1,19 @@
+echo "code blocks"
+
+rc=0
+
+echo -n '  format for code block html ....... '
+
+SEP='
+    this is
+    code
+'
+
+count=`echo "$SEP" | ./markdown | wc -l`
+
+if [ $count -eq 3 ]; then
+    echo "ok"
+else
+    echo "FAILED"
+    rc=1
+fi