Improved version show.

Makefile

@@ -1,4 +1,4 @@
 default:
-	echo "-define(VERSION,\"`git rev-parse HEAD | head -c 6`\")." > include/mad.hrl
+	echo "-define(VERSION,\"`git describe --tags`\")." > include/mad.hrl
 	erlc -o ebin deps/ling/bc/*.erl || true
 	./mad cle dep com str bun mad