add script to import commonmark tests into md/html fixtures.

Place http://spec.commonmark.org/0.28/spec.json in test/ folder first. Then `cd test` and `node import.js <section_name`, and move the generated fixtures into the new/ folder

test/import.js

@@ -0,0 +1,28 @@
+var fs = require('fs');
+var marked = require('../');
+
+//var nested = [349, 353, 369, 387, 388, 389, 392, 395, 396, 402, 403, 404, 409, 438, 440, 441, 442, 443, 445];
+
+if (process.argv.length !== 3) {
+	console.warn(`Usage: node ${__filename} '<test_section>'`);
+	console.warn('<test_section> must match one in spec.json');
+	process.exit(1);
+}
+
+var name = process.argv[2];
+
+var all = JSON.parse(fs.readFileSync('spec.json', 'utf8'));
+var md = `${name}\n===================\n\n`;
+var html = marked(md) + '\n';
+
+for (var test of all.filter(t => t.section == name )) {
+	var heading = `### Example ${test.example}\n`;
+	md += heading + '\n' + test.markdown + '\n';
+	html += marked(heading) + '\n' + test.html + '\n';
+}
+
+var slug = name.toLowerCase().replace(/\s+/, '_');
+fs.writeFileSync(`cm_${slug}.md`, md);
+fs.writeFileSync(`cm_${slug}.html`, html);
+
+console.log(`Saved in cm_${slug}.md and cm_${slug}.html`);