Fix scheme-matching regexp.

Old behavior allowed underscores and schemes starting with a digit,
and did not allow -+.
New behavior: https://tools.ietf.org/html/rfc3986\#section-3.1

Side effect: closes GH-1146

plugins/URL/test.py

@@ -80,6 +80,10 @@ class URLTestCase(ChannelPluginTestCase):
         self.feedMsg(urls[0])
         self.assertResponse('url last', urls[0])
 
+    def testStripsColors(self):
+        self.feedMsg('\x031foo \x034' + urls[0])
+        self.assertResponse('url last', urls[0])
+
     def testAction(self):
         self.irc.feedMsg(ircmsgs.action(self.channel, urls[1]))
         self.assertNotRegexp('url last', '\\x01')

src/utils/web.py

@@ -80,9 +80,10 @@ _octet = r'(?:2(?:[0-4]\d|5[0-5])|1\d\d|\d{1,2})'
 _ipAddr = r'%s(?:\.%s){3}' % (_octet, _octet)
 # Base domain regex off RFC 1034 and 1738
 _label = r'[0-9a-z][-0-9a-z]*[0-9a-z]?'
+_scheme = r'[a-z][a-z0-9+.-]*'
 _domain = r'%s(?:\.%s)*\.[0-9a-z][-0-9a-z]+' % (_label, _label)
-_urlRe = r'(\w+://(?:\S+@)?(?:%s|%s)(?::\d+)?(?:/[^\])>\s]*)?)' % (_domain,
-                                                                   _ipAddr)
+_urlRe = r'(%s://(?:\S+@)?(?:%s|%s)(?::\d+)?(?:/[^\])>\s]*)?)' % (
+        _scheme, _domain, _ipAddr)
 urlRe = re.compile(_urlRe, re.I)
 _httpUrlRe = r'(https?://(?:\S+@)?(?:%s|%s)(?::\d+)?(?:/[^\])>\s]*)?)' % \
              (_domain, _ipAddr)