- add support for correlations to propagate all the way in; because
correlations require context now, need to make sure a select enclosure
of any level takes effect any number of levels deep.
- fix what we said correlate_except() was supposed to do when we first
released #2668 - "the FROM clause is left intact if the correlated SELECT
is not used in the context of an enclosing SELECT..." - it was not
considering the "existing_froms" collection at all, and prohibited
additional FROMs from being placed in an any() or has().
- add test for multilevel any()
- lots of docs, including glossary entries as we really need to define
"WHERE clause", "columns clause" etc. so that we can explain correlation better
- based on the insight that a SELECT can correlate anything that ultimately
came from an enclosing SELECT that links to this one via WHERE/columns/HAVING/ORDER BY,
have the compiler keep track of the FROM lists that correspond in this way,
link it to the asfrom flag, so that we send to _get_display_froms() the exact
list of candidate FROMs to correlate.  no longer need any asfrom logic in the
Select() itself
- preserve 0.8.1's behavior for correlation when no correlate options are given, not
to mention 0.7 and prior's behavior of not propagating implicit correlation more than one level..
this is to reduce surprises/hard-to-debug situations when a user isn't trying
to correlate anything.

Conflicts:
	doc/build/changelog/changelog_08.rst
	doc/build/changelog/changelog_09.rst
	lib/sqlalchemy/sql/compiler.py

to a DBLINK remote database; while the syntax has been present in the
Oracle dialect for some time, up until now it has never been tested.
The syntax has been tested against a sample database linking to itself,
however there's still some uncertainty as to what should be used for the
"owner" when querying the remote database for table information.
Currently, the value of "username" from user_db_links is used to
match the "owner".  [ticket:2619]

could be lost if the statement were used as a subquery
inside of another statement, as well as other similar
situations.  Among other things, would cause
typing information to be lost when the Oracle/mssql dialects
would apply limit/offset wrappings. [ticket:2603]

- build a new Sphinx extension that allows dialect info
to be entered as directives which is then rendered consistently
throughout all dialect/dbapi sections
- break out the "empty_strings" requirement for oracle test

- begin consolidating docs for dialects to be more self contained
- add a separate section for "external" dialects
- not sure how we're going to go with this yet.