Add test/bin/lex.js utility

Helpful binary when developing / debugging

test/bin/lex.js

@@ -0,0 +1,16 @@
+#!/usr/bin/env node
+
+var fs = require('fs');
+
+var gitbook = require('../../');
+
+if(process.argv < 3) {
+    console.error('Please specify a filename');
+    process.exit(1);
+}
+
+var content = fs.readFileSync(process.argv[2], 'utf8');
+
+var lexed = gitbook.parse.lex(content);
+
+console.log(JSON.stringify(lexed, null, 2));