read Atom and RSS feeds: Stack Overflow answers through the open /feeds door

Sites behind hard bot challenges often leave their feeds open. distill()
now detects feed XML, converts entries (title, byline, link, escaped HTML
body) into a plain HTML document, and everything downstream is unchanged.
fetch accepts xml content types. Ships a stackoverflow.com spec mapping
question/tag/user onto the feed URLs.

Live: oc open on a Stack Overflow question feed renders ~493 tokens vs
~29k for the page HTML, HTTP 200 where the HTML page is challenged.

clis/stackoverflow.com.json

@@ -0,0 +1,9 @@
+{
+  "domain": "stackoverflow.com",
+  "commands": {
+    "question": { "open": "https://stackoverflow.com/feeds/question/{id}", "args": ["id"] },
+    "tag": { "open": "https://stackoverflow.com/feeds/tag?tagnames={name}&sort=newest", "args": ["name"] },
+    "user": { "open": "https://stackoverflow.com/feeds/user/{id}", "args": ["id"] },
+    "recent": { "open": "https://stackoverflow.com/feeds" }
+  }
+}