Issue #2338727 by znerol, almaudoh: Replace static SessionManager::$enabled property with WriteSafeSessionHandler class and resolve hidden circular dependency between SessionManager and SessionHandler

Revert "Issue #2229145 by znerol, neclimdul, larowlan, joelpittet, almaudoh: Register symfony session components in the DIC and inject the session service into the request object"

This reverts commit b926f5d8.

Issue #2229145 by znerol, neclimdul, larowlan, joelpittet, almaudoh: Register symfony session components in the DIC and inject the session service into the request object

Issue #2347877 by znerol, Berdir: Move DrupalKernel::initializeCookieGlobals() into a SessionConfiguration service

Issue #2330279 by znerol: Fixed When operating in mixed mode SSL: data from anonymous non-HTTP session is still available after login.

Issue #2256257 by znerol, cosmicdreams | YesCT: Move token seed in SessionManager in isSessionObsolete() and regenerate()  to the MetadataBag.

Issue #2245003 by znerol, YesCT, sun, damiankloip: Use a random seed instead of the session_id for CSRF token generation.

Issue #2239181 by sun, znerol: SessionManager::isStarted() returns TRUE even after session_write_close() has been called.

Issue #2228341 by sun, znerol, skipyT, ParisLiakos: Objectify session management functions + remove session.inc.