dl-e621: support downloading posts by ID or MD5

dl-e621.js

@@ -4,6 +4,11 @@ import { dl, get } from './_shared.js';
 
 await dl(
 	async function*(query) {
+		if (/^[0-9]+$/.test(query)) {
+			query = `id:${query}`;
+		} else if (/^[0-9a-f]{32}$/i.test(query)) {
+			query = `md5:${query}`;
+		}
 		for (let page = null, posts; !posts || posts.length === 320; page = `b${posts[319]?.id}`) {
 			posts = (await (await get('https://e621.net/posts.json', { limit: 320, page, tags: query })).json()).posts;
 			yield posts.map(post => ({