- some more query tests
- removed warnings from testbase to appease the buildbots

- the two mapper PK tests should actually warn on the id column collision
- reverted abc_inheritance back to normal

  columns from a join, equating foreign keys and otherwise equated columns.
  this is also mostly to help inheritance scenarios formulate the best
  choice of primary key columns.  [ticket:185]
- added 'bind' argument to Sequence.create()/drop(), ColumnDefault.execute()

- Deprecated BoundMetaData- use MetaData instead
- Removed DMD and BMD from documentation

- Test runs can now --require a particular external package version
- Added some 'coerce' magic to the Oracle connection factory to support use_ansi in the dburl query string

the mapper would then always apply query "wrapping" behavior
for all subsequent LIMIT/OFFSET/DISTINCT queries, even if no
eager loading was applied on those subsequent queries.

- much more functionality moved into ExecutionContext, which impacted
the API used by dialects to some degree
- ResultProxy and subclasses now designed sanely
- merged patch for #522, Unicode subclasses String directly,
MSNVarchar implements for MS-SQL, removed MSUnicode.
- String moves its "VARCHAR"/"TEXT" switchy thing into
"get_search_list()" function, which VARCHAR and CHAR can override
to not return TEXT in any case (didnt do the latter yet)
- implements server side cursors for postgres, unit tests, #514
- includes overhaul of dbapi import strategy #480, all dbapi
importing happens in dialect method "dbapi()", is only called
inside of create_engine() for default and threadlocal strategies.
Dialect subclasses have a datamember "dbapi" referencing the loaded
module which may be None.
- added "mock" engine strategy, doesnt require DBAPI module and
gives you a "Connecition" which just sends all executes to a callable.
can be used to create string output of create_all()/drop_all().