In STOPPING state, the primary:
1. rejects all clients and any new node
2. finalize remaining transactions
   (i.e. those for which a tcp_finish was received)
3. finally shut down all nodes of the cluster

During election, nodes are not identified anymore.
testElectionWithManyMasters only worked thanks to the election timeout.

Also, change the way TTIDs are generated in preparation for that bug's fix:
we will need TTID to be monotonous across master restarts and TID generator
provides this feature.

This should never trigger, as gmtime bases itself on a unix epoch
timestamp which is non-monotonous on leap seconds. So gmtime cannot
return second count above 59.

Prepares for type change so it is easily reversible.

Fixes two bugs:
- IPv6 addresses are now put in canonical form.
- non-IPv6 port-less addresses are resolved.
Also, simplify url-style IPv6 parsing.
Also, rename "ip" into more generic naming "host".

The only case where UUID persistence matters is on storage nodes, and it
is already restored from database if available.

Missed in 4df3c4e1.

Since lib.protocol has been rewritten to be semantic-oriented and
duplicates a lot less code, this test is just bloated (testing the same
code over and over) and a maintenance burden.

It is intended to raise even when running in optimised mode. The intent of
that change was to allow interpreter to detect the last elif is not
expected to be needed (although it is not known to make such deductions
currently). If only python had a deeper "enum" notion...
This (very) partially reverts f32e9120.

Also, log node's final UUID, not the one it advertised.

Also, tweak condition order to accelerate the most likely case: it is
expected to have more clients than storage nodes, more storage nodes than
master nodes, more master nodes than admin nodes and no unknown node type.

In turn, stop returning uuid from identifyNode.