Issue #1609760 by chx, sun: Fixed hook_image_style_()*() is not invoked for image styles upon Image module installation.

Issue #1599306 by bojanz, exratione: Fixed field_sync_field_status() needlessly rebuilds module data, slows down installation dramatically.

Issue #1666632 by sun, chx: Add Config::isNew() to allow code to determine whether a config object already exists.

Issue #1496542 by cosmicdreams, sun, chx, vasi1186, aspilicious, alexpott, nadavoid, Pedro Lozano, disasm, andypost | heyrocker: Convert site information to config system.

- Patch #7881 by pwolanin, mikeytown2, gwynnebaer, Patrizio, sylus, effulgentsia: add support to drupal_http_request() for proxy servers.

Issue #1605324 by sun, Jose Reyero, alexpott, chx, Rob Loach | beejeebus: Configuration system cleanup and rearchitecture.

Revert "- Patch #1605324 by sun, Jose Reyero, alexpott, chx, Rob Loach, beejeebus: configuration system cleanup and rearchitecture."

This reverts commit 8df23c8a. Original commit
was missing some files. Trying again.

- Patch #1605324 by sun, Jose Reyero, alexpott, chx, Rob Loach, beejeebus: configuration system cleanup and rearchitecture.

Issue #1619446 by Niklas Fiekas: Fixed All autocomplete and drupal_json_output() responses are broken (returning Ajax instead of JSON).

- Patch #1651010 by pounard: HttpKernel patch introduces ob_flush() related PHP warnings on my environement, potential patch and performance improvement.

- Patch #1263208 by Niklas Fiekas, BTMash, aiwata55, Berdir, kathyh: upgrade path for blog module removal.

- Patch #1525138 by twistor, Georgique: Fixed Illegal string offset 'field' in function TaxonomyTermController->buildQuery().

- Patch #7881 by mikeytown2, gwynnebaer, Patrizio, sylus, effulgentsia: add support to drupal_http_request() for proxy servers.

Issue #1599554 by sun, dww, effulgentsia: Tutorial/guidelines for how to convert variables into configuration.

Issue #1424924 by Rob Loach: Added Use Composer for updating Symfony components (without removing Symfony code from repo).

- Patch #1260800 by David_Rothstein, lewisnyman, yoroy, nod_, thedavidmeister, effulgentsia: kill the overlay for widths below 640 pixels.

Issue #1658164 by Rob Loach, Berdir: Fixed TableSort Class not found exception thrown in database_test_theme_tablesort().

Issue #1619084 by kiamlaluno: Update documentation for drupal_render to reflect current function code

Issue #1552400 by mjonesdinero, SumeetSingh: Fix documentation for user_is_blocked, which was misleading.

Issue #1635084 by webflo, penyaskito, vasi1186, Berdir: Fixed Fatal error when deleting language due to DBTNG typo.