ur'string' is Py3 SyntaxError, use u'string' instead

$ python2
```
$ python2
Python 2.7.13 (default, Jul 18 2017, 09:17:00)
[GCC 4.2.1 Compatible Apple LLVM 8.1.0 (clang-802.0.42)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> ur"[\w\u2E80-\u9FFF]" == u"[\w\u2E80-\u9FFF]"
True
>>> ur"[\w\u2E80-\u9FFF]" == r"[\w\u2E80-\u9FFF]"
False
```

exts/smallseg.py

@@ -86,7 +86,7 @@ class SEG(object):
                     elif mem2!=None:
                         delta = mem2[0]-i
                         if delta>=1:
-                            if (delta<5) and (re.search(ur"[\w\u2E80-\u9FFF]",t)!=None):
+                            if (delta<5) and (re.search(u"[\w\u2E80-\u9FFF]",t)!=None):
                                 pre = text[i-j]
                                 #print pre
                                 if not (pre in self.specialwords):
@@ -141,4 +141,4 @@ class SEG(object):
             recognised.append(text[i-j:i])        
         else:
             recognised.extend(self._pro_unreg(text[i-j:z]))
-        return recognised
+        return recognised