Unbreak Erlang client.
Merge default
Names for client network connections.
Make the name of an amqp_client network connection distinguishable from an incoming server one.
Add process names for all connection-level processes in the AMQP client.

** network **

amqp_gen_connection
amqp_channels_manager
rabbit_writer
amqp_main_reader
heartbeat_{sender,receiver}

** direct **

amqp_gen_connection
amqp_channels_manager
rabbit_queue_collector

This has a couple of knock-on effects: amqp_channels_manager and amqp_main_reader get promoted to gen_server2s, and more importantly we need to fiddle with the order of starting connection infrastructure (to start the channels manager after the socket in the network case). I *think* this counts as a net simplification (since the chmgr is now started with the other infrastructure rather than being a special case) but it does mean that Mod:connect/4 now needs to know about and return the ChMgr.
Oops
Process identities for per-channel processes in the Erlang client.
Revert changes to add proc_name via gen_server2, instead do it explicitly with a helper macro.
Merge bug25910