Issue #1015946 by pillarsdotnet, catch, bfroehle, Jej, jose.guevara, Damien Tournoud: Fixed Eliminate ->cache and {session}.cache in favor of ['cache_expiration()'][].

- Patch #692044 by Damien Tournoud, effulgentsia: a site with statistics module enabled is much slower in serving cached pages in D7 than in D6.

- Patch #325169 by mundanity, Arancaytar, Crell, chx, picco, alexw: move error/exception handler higher up in the bootstrap process.

#333171 by catch: Provide cache_get_multiple() and allow clearing of multiple cache IDs at once (with tests).

- Patch #302763 by Dave Reid, Rob Loach: replace time() by ['REQUEST_TIME'] as per Rasmus' suggestion.  Removed drupal_referrer() for consistency.

- Patch #225450 by Crell, chx, bjaspan, catch, swentel, recidive et al: next generation database layer for Drupal 7.

- Patch #277440 by R.Muilwijk: fixed bug caching integers and doubles.  Fixes 2 of the 3 failing cache tests.

- Patch #245115 by kkaefer, John Morahan, JohnAlbin et al: after a long discussion we've decided to make the concatenation operator consistent with the other operators.

#215252 by bdragon: reset the cache flush variable before the cache is flushed, so busy sites will not attempt multiple cache flushes at a time