core: implement bind host support

Closes #379.

classes.py

@@ -201,6 +201,10 @@ class Irc():
                 self.socket = socket.socket(stype)
                 self.socket.setblocking(0)
 
+                # Set the socket bind if applicable.
+                if 'bindhost' in self.serverdata:
+                    self.socket.bind((self.serverdata['bindhost'], 0))
+
                 # Set the connection timeouts. Initial connection timeout is a
                 # lot smaller than the timeout after we've connected; this is
                 # intentional.

example-conf.yml

@@ -88,6 +88,9 @@ servers:
         recvpass: "abcd"
         sendpass: "abcd"
 
+        # Set the bind host, useful for multi-homed hosts.
+        #bindhost: 1.2.3.4
+
         # The full network name, used by plugins.
         netname: "InspIRCd Network"