view.  So copy collections.OrderedDict and use MutableMapping to set up
keys, items, values on our own OrderedDict.

Conflicts:
	lib/sqlalchemy/engine/base.py

for an INSERT or UPDATE are now sorted when they contribute towards
the "compiled cache" cache key.   These keys were previously not
deterministically ordered, meaning the same statement could be
cached multiple times on equivalent keys, costing both in terms of
memory as well as performance.
fixes #3165

rules, better message formatting

events from firing for those statements which it uses internally
to detect if a table exists or not.   This is achieved using an
execution option ``skip_user_error_events`` that disables the handle
error event for the scope of that execution.   In this way, user code
that rewrites exceptions doesn't need to worry about the MySQL
dialect or other dialects that occasionally need to catch
SQLAlchemy specific exceptions.

to get all flake8 passing

in all cases unconditionally, the number of use cases that go beyond what
dbapi_error() is expecting has gone too far for an 0.9 release.
Additionally, the number of things we'd like to track is really a lot
more than the five arguments here, and ExecutionContext is really not
suitable as totally public API for this.   So restore dbapi_error
to its old version, deprecate, and build out handle_error instead.
This is a lot more extensible and doesn't get in the way of anything
compatibility-wise.