Example output:

    stress: yes (toggle with F1)
    cluster state: RUNNING
    last oid: 0x44c0
    last tid: 0x3cdee272ef19355 (2019-02-26 15:35:11.002419)
    clients: 2308, 2311, 2302, 2173, 2226, 2215, 2306, 2255, 2314, 2356 (+48)
            8m53.988s (42.633861/s)
    pt id: 4107
        RRRDDRRR
     0: OU......
     1: ..UO....
     2: ....OU..
     3: ......UU
     4: OU......
     5: ..UO....
     6: ....OU..
     7: ......UU
     8: OU......
     9: ..UO....
    10: ....OU..
    11: ......UU
    12: OU......
    13: ..UO....
    14: ....OU..
    15: ......UU
    16: OU......
    17: ..UO....
    18: ....OU..
    19: ......UU
    20: OU......
    21: ..UO....
    22: ....OU..
    23: ......UU

'title' means both process name and command line.

This is cosmetics so it won't fail if the 'setproctitle' module
is not available.

A new subprocess is used to:
- fetch data from the source DB
- repickle to change oids (when merging several DB)
- compress
- checksum

This is mostly useful for the second step, which is relatively much slower than
any other step, while not releasing the GIL.

By using a second CPU core, it is also often possible to use a better
compression algorithm for free (e.g. zlib=9). Actually, smaller data can speed
up the writing process.

In addition to greatly speed up the import by parallelizing fetch+process with
write, it also makes the main process more reactive to queries from client
nodes.

zodburi[1] provides a way to open ZODB storages by URL/URI. It already
has support for file:// zeo:// zconfig:// memory:// etc schemes out of
the box and third-party-to-ZODB storages can add support for their
schemes via providing zodburi.resolvers entrypoint.

For example relstorage and newtdb do this.

Let's also teach NEO to open itself via neo:// URI schema.

[1] http://docs.pylonsproject.org/projects/zodburi
[2] https://github.com/zodb/relstorage/blob/2.1a1-15-g68c8cf1/relstorage/zodburi_resolver.py
[3] https://github.com/newtdb/db/blob/0.5.2-1-gbd36e90/src/newt/db/zodburi.py

SourceForge currently has too many issues.

This fixes:

Traceback (most recent call last):
  File "neo/tests/functional/testMaster.py", line 50, in testStoppingSecondaryMaster
    self.neo.expectDead(master)
  File "neo/tests/functional/__init__.py", line 615, in expectDead
    self.expectCondition(callback, *args, **kw)
  File "neo/tests/functional/__init__.py", line 509, in expectCondition
    'History: %s' % opaque_history)
AssertionError: Timeout while expecting condition. History: [False, False, False, False, False, False, False, False, False, False, False]

Next version is actually a metapackage depending on:
  persistent 4.0
  BTrees 4.0
  ZODB 4.0
  ZEO 4.0

Note that version '123dev' is considered lower than '123'

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.

Replication is also fully reimplemented:
- It is not done anymore on whole partitions.
- It runs at lowest priority not to degrades performance for client nodes.

Schema of MySQL table is changed to optimize storage layout: rows are now
grouped by age, for good partial replication performance.
This certainly also speeds up simple loads/stores.