- add a connect=True key to connection record to support
  pre-loading of _ConnectionRecord objects
- ensure _ConnectionRecord.close() leaves the record in a good
  state for reopening
- add _ConnectionRecord.record_info for persistent storage
- add "in_use" accessor based on fairy_ref being present or not
- allow for the exclusions system and SuiteRequirements to be
  usable without the full plugin_base setup.
- move some Python-env requirements to the importable
  requirements.py module.
- allow starttime to be queried
- add additional events for engine plugins
- have "dialect" be a first-class parameter to the pool,
  ensure the engine strategy supplies it up front

Change-Id: Ibf549f7a1766e49d335cd6f5e26bacfaef9a8229

Fixed bug where the "simple many-to-one" condition that allows  lazy
loading to use get() from identity map would fail to be  invoked if the
primaryjoin of the relationship had multiple clauses separated by AND
which were not in the same order as that of the primary key columns
being compared in each clause. This ordering
difference occurs for a composite foreign key where the table-bound
columns on the referencing side were not in the same order in the .c
collection as the primary key columns on the referenced side....which
in turn occurs a lot if one is using declarative mixins and/or
declared_attr to set up columns.

Change-Id: I66cce74f614c04ed693dc0d58ac8c952b2f8ae54
Fixes: #3788

Fixed regression in JSON datatypes where the "literal processor" for
a JSON index value, that needs to take effect for example within DDL,
would not be invoked for the value.  The native String and Integer
datatypes are now called upon from within the JSONIndexType
and JSONPathType.  This is applied to the generic, Postgresql, and
MySQL JSON types.

Change-Id: Ifa5f2acfeee57a79d01d7fc85d265a37bd27c716
Fixes: #3765

this must have been an oversight.   Leave mysql.JSON in place still
as we might need to add things to it.
- CAST(json, String) still confusing MySQL drivers even mysqlclient.
Since here we're checking for the raw form of the JSON and not a typical
round trip, add a force for unicode

Change-Id: I727f4526a01a0875037cf0dede45cd074da5205a

Change-Id: I2dc6961f9b692a8bb6bfb2296d159df145dec679

Regarding 0e88bcc30ed49193b91f248123f526fa30007f22, "options"
needs to be present as a key in the dictionary because Alembic
uses this as a guide to know if the backend is even capable of
reporting on foreign key options.

Change-Id: I271090f75088cfeec24315a878060f9b8a265335

run to prevent race conditions against concurrent runs

Change-Id: I065d1cec346ea7af03792c3cc2f30766f73c2bd3

sometimes and it really breaks the build once this
error occurs.

Change-Id: I577c78d623b22a6429f8b083fe08821bc467eb7a