fix gfm extended autolinking requiring multiple backpedals

Add a test and fix that trailing punctuation is omitted in link URLs for
markdown like this:

    (See https://www.example.com/fhqwhgads.)

The trailing period and closing parenthesis should not be part of the
link URL.

lib/marked.js

@@ -655,7 +655,8 @@ InlineLexer.prototype.output = function(src) {
       text,
       href,
       title,
-      cap;
+      cap,
+      prevCapZero;
 
   while (src) {
     // escape
@@ -681,7 +682,10 @@ InlineLexer.prototype.output = function(src) {
 
     // url (gfm)
     if (!this.inLink && (cap = this.rules.url.exec(src))) {
-      cap[0] = this.rules._backpedal.exec(cap[0])[0];
+      do {
+        prevCapZero = cap[0];
+        cap[0] = this.rules._backpedal.exec(cap[0])[0];
+      } while (prevCapZero !== cap[0]);
       src = src.substring(cap[0].length);
       if (cap[2] === '@') {
         text = escape(cap[0]);

test/specs/marked/marked-spec.js

@@ -32,6 +32,21 @@ Messenger.prototype.test = function(spec, section, ignore) {
 
 var messenger = new Messenger();
 
+describe('Marked Autolinks', function() {
+  var section = 'Autolinks';
+
+  // var shouldPassButFails = [];
+  var shouldPassButFails = [];
+
+  var willNotBeAttemptedByCoreTeam = [];
+
+  var ignore = shouldPassButFails.concat(willNotBeAttemptedByCoreTeam);
+
+  markedSpec.forEach(function(spec) {
+    messenger.test(spec, section, ignore);
+  });
+});
+
 describe('Marked Code spans', function() {
   var section = 'Code spans';
 

test/specs/marked/marked.json

@@ -1,4 +1,10 @@
 [
+  {
+    "section": "Autolinks",
+    "markdown": "(See https://www.example.com/fhqwhgads.)",
+    "html": "<p>(See <a href=\"https://www.example.com/fhqwhgads\">https://www.example.com/fhqwhgads</a>.)</p>",
+    "example": 10
+  },
   {
     "section": "Code spans",
     "markdown": "`someone@example.com`",