entry points. loading the built-in database dialects works the
same as always, but if none found will fall back to trying
pkg_resources to load an external module [ticket:521]
arguments must be consumed by one of the dialect, connection pool, and engine
constructors, else a TypeError is thrown which describes the full set of
invalid kwargs in relation to the selected dialect/pool/engine configuration.
arguments specified in query string, 'connect_args' argument
to 'create_engine', or custom creation function via 'creator'
function to 'create_engine'.
- added "recycle" argument to Pool, is "pool_recycle" on create_engine,
defaults to 3600 seconds; connections after this age will be closed and
replaced with a new one, to handle db's that automatically close
stale connections [ticket:274]
Mike Bayer