Commit aa4d621d broke log rotation
and neolog sometimes failed to read in new format.

neolog has new options: -N for old behaviour, and -C to show the cluster name.

Now that we do inequality comparisons between timestamps, the master must
use a monotonic clock, to avoid issues when the clock is turned back.
Before, the probability that time.time() returned again the same value was
probably negligible.

- format IPv6 inside [] when followed by :<port>
- unify rendering of node lists
- neoctl: do not crash on empty DB (no PT id)

The added test describes how the new id timestamps fix the race condition.
These timestamps could be any unique opaque values, and the protocol is
extended to exchange them along with node ids.

Internally, nodes also reuse timestamps as a marker to identify the first
NotifyNodeInformation packets from the master: since this packet is a complete
list of nodes in the cluster, any other node in the node manager has left the
cluster definitely and is removed.

The secondary masters didn't receive update about master nodes.
It's also useless to send them information about non-master nodes.

They're decompressed automatically to temporary files.

It would be unreliable to resume printing logs using a condition on date,
so the format of log files is changed to add primary keys that number records.

The main goal of this patch is to keep all DEBUG logs and packet logger enabled
without exploding disk usage.
This is done by keeping the last 16 MB (by default) of debugging information in
a RAM buffer, and to emit it to an SQLite DB upon RTMIN signal or in case of
warning and more severe log.

Implementation is also cleaned up for better integration within a framework
or if run standalone. NEO logger is now a direct child of root handler.
Only warnings and more severe logs are forwarded to root handler.

A new script 'neolog' is added to pretty-print the contents of the SQLite log.

In unit tests, logging events are not buffered but emitted immediately.
When a test passes, payloads of all exchanged packets are discarded to reduce
disk usage on test bots.

This slows down performance tests by about 15 % because even if nothing is
written to disk, debug and packet log records are now always rendered.