Use attrs, to remove verbose __init__ and __repr__ methods

Backwards compatibility is strictly preserved in `__init__`, including parameter names, defaults and position. Whenever that's difficult using `attrs`, the custom `__init__` is kept instead (for the time being).

`__repr__` methods have changed to the format `attrs` use, but people don't rely on this for anything other than debug output, so it shouldn't be a problem.

fbchat/_thread.py

@@ -1,6 +1,7 @@
 # -*- coding: UTF-8 -*-
 from __future__ import unicode_literals
 
+import attr
 from ._core import Enum
 
 
@@ -42,23 +43,24 @@ class ThreadColor(Enum):
     BILOBA_FLOWER = "#a695c7"
 
 
+@attr.s(cmp=False, init=False)
 class Thread(object):
     """Represents a Facebook thread"""
 
     #: The unique identifier of the thread. Can be used a `thread_id`. See :ref:`intro_threads` for more info
-    uid = None
+    uid = attr.ib(converter=str)
     #: Specifies the type of thread. Can be used a `thread_type`. See :ref:`intro_threads` for more info
-    type = None
+    type = attr.ib()
     #: A url to the thread's picture
-    photo = None
+    photo = attr.ib(None)
     #: The name of the thread
-    name = None
+    name = attr.ib(None)
     #: Timestamp of last message
-    last_message_timestamp = None
+    last_message_timestamp = attr.ib(None)
     #: Number of messages in the thread
-    message_count = None
+    message_count = attr.ib(None)
     #: Set :class:`Plan`
-    plan = None
+    plan = attr.ib(None)
 
     def __init__(
         self,
@@ -77,9 +79,3 @@ class Thread(object):
         self.last_message_timestamp = last_message_timestamp
         self.message_count = message_count
         self.plan = plan
-
-    def __repr__(self):
-        return self.__unicode__()
-
-    def __unicode__(self):
-        return "<{} {} ({})>".format(self.type.name, self.name, self.uid)