update loxigen-artifacts

Pulls in of_object_new_from_message_preallocated.
retain ownership of incoming messages in OFConnectionManager

This simplifies the OFStateManager handlers which no longer need to free the
message when they're finished with it. Handlers that pass the message to a long
running task dup it first.

The end goal is to use the message directly from the OFConnectionManager wire
buffer without needing to copy it first.
OFConnectionManager: zero-allocation message reading

The empty ind_cxn_message_track_setup in the utest was a bug.
indigo: remove dead declaration
fix a few memory leaks

I looked at all of_.*_new calls.
Merge into master from pull request #93:
message ownership (https://github.com/floodlight/indigo/pull/93)