added a timeout api

[cfsego]

--- /home/cfsego/.local/lib/python3.5/site-packages/socks.py    2017-05-08 21:08:01.781956877 +0800
+++ socks.py    2017-05-08 21:05:47.601957161 +0800
@@ -154,6 +154,14 @@
                                 username.encode() if username else None,
                                 password.encode() if password else None)
 
+def set_default_timeout(timeout=None):
+    """
+    set_default_timeout(timeout)
+
+    Sets a default timeout which all further socksocket objects will use.
+    """
+    socksocket.default_timeout = timeout
+
 def setdefaultproxy(*args, **kwargs):
     if 'proxytype' in kwargs:
         kwargs['proxy_type'] = kwargs.pop('proxytype')
@@ -276,6 +284,7 @@
     """
 
     default_proxy = None
+    default_timeout = None
 
     def __init__(self, family=socket.AF_INET, type=socket.SOCK_STREAM, proto=0, *args, **kwargs):
         if type not in (socket.SOCK_STREAM, socket.SOCK_DGRAM):
@@ -292,7 +301,7 @@
         self.proxy_sockname = None
         self.proxy_peername = None
 
-        self._timeout = None
+        self._timeout = self.default_timeout 
 
     def _readall(self, file, count):
         """

[Anorov]

Could you submit this as a PR, please? Thank you.