High: cib: Performance improvements for non-DC nodes

Only generate a slave update if something actually changed.
Detect ordering changes by comparing digests on the DC instead, but
rearrange the code so that we can cache the previous value.
Low: Core: Obtain more data when an IPC request times out
Log: ipc: Correctly log disconnected sessions after calling qb_ipcs_response_sendv()
Log: cib: Log when forwarding messages
Log: Require some xml logging to be enabled explicitly, even for the blackbox
Log: cib: Find out why some commands take a long time
Refactor: Core: A faster and more consistant digest function

Combine the filtering and dumping stages when creating the input for
crm_md5sum().  xmlNodeDump() was sometimes super fast (<1s) but other
times super slow (4s or so) for the same input.
Log: More xml that needs to be explicitly enabled
Fix: crmd: Prevent use-after-free of fsa_message_queue during exit