Add a document describing how the Python code is arranged, for people…

… interested

in hacking on it.  Mention the use_threading option in the Connection constructor.

docs/code_layout.txt

@@ -0,0 +1,44 @@
+General layout of the Python code for those interested in hacking on it.
+------------------------------------------------------------------------
+
+The Connection class in connection.py is the heart of the library, it
+opens the TCP connection, optionally wraps it in SSL, wires together
+the various other classes.
+
+MethodReader and MethodWriter in method_framing.py should not be visible
+to the amqplib user.  MethodReader is where the option for threading is
+implemented.
+
+AMQPReader and AMQPWriter are reused it many other places within the
+Channel and Connection classes, not just in the layer shown below.
+
+This is the general arrangement of how the classes communicate with
+each other:
+
+                           +-----------+        +-----------+
+channel.py                 |  Channel  |   ...  |  Channel  |
+                           +-----------+        +-----------+
+                                 ^                    ^
+                                 |                    |
+                                 V                    V
+                        +--------------------------------------+
+connection.py           |               Connection             |
+                        +-------+------------------------------+
+                                |                      ^
+                                |                      |
+                                V                      |
+                        +----------------+    +--------+-------+
+method_framing.py       |  MethodWriter  |    |  MethodReader  |
+                        +-------+--------+    +----------------+
+                                |                      ^
+                                |                      |
+                                V                      |
+                        +----------------+    +--------+-------+
+serialization.py        |  AMQPWriter    |    |  AMQPReader    |
+                        +-------+--------+    +----------------+
+                                |                      ^
+                                |                      |
+                                V                      |
+                            +--------------------------+--+
+                            |TCP Socket, perhaps with SSL |
+                            +-----------------------------+

docs/overview.txt

@@ -25,6 +25,11 @@ Some examples for creating a Connection object:
     conn = amqp.Connection(host='1.2.3.4:5672', ssl=True)
     conn = amqp.Connection(userid='foo', password='bar')
 
+Non-blocking waits, timeouts, and flow-control require that an
+optional threading mode be enabled with: use_threading=True, as in:
+
+    conn = amqp.Connection('1.2.3.4', use_threading=True)
+
 Connections are closed with the close() method
 
     conn.close()