Issue #393538 by Liam Morland, valthebald, dmitrig01, David_Rothstein: Document that check_plain() can issue PHP messages on invalid UTF-8 input.

Issue #1918820 by neclimdul, typhonius, girishmuraly, pwolanin | 0x534B41: Fixed HTTP header date formats to follow RFC 7231 rather than RFC 1123.

Issue #2228825 by donquixote | pingwin4eg: Fixed drupal_get_filename() does not search the filesystem when the file isn't yet listed in the {system} table in the database.

Issue #667098 by catch, chx, plach, Fabianx: Fixed a bug which caused drupal_get_bootstrap_phase() to abort the bootstrap when called early in the page request.

Issue #1201088 by crazyrohila, pjcdawkins, eiriksm, Zgear, barbi | alxsvdr: Drupal_environment_initialize() passes wrong ini_set parameter.

Issue #1476810 by Spleshka, David_Rothstein, franz | Heine: Drupal_serve_page_from_cache can serve uncompressed data with Content-Encoding gzip header with page_cache_without_database = 1.

Issue #1399798 by nevergone, amateescu, chriscohen: Add a variable to allow the anonymous user object to not be a stdClass and to work around the fact that anonymous user properties are hardcoded.

Issue #692366 by  mariacha1, hosef, Albert Volkman, xjm, underq, kid_icarus, willmoy, bradweikel: Replace US-centric php.net URLs with language-neutral URLs

Issue #1453984 by xjm, naxoc, Dave Reid, underq, dags, tim.plunkett, Heine: Fixed Color module doesn't test for unlimited memory.

Issue #606598 by andypost, BarisW, stBorchert, David_Rothstein, sun, aspilicious, joachim, danielbeeke2, Sutharsan: Added human readable labels to image styles.

Issue #1811520 by JacobSanford, lirantal: Add section tags to theme, hook_menu, and t documentation.

Issue #1739986 by RobLoach, pwolanin, sun, Berdir, moshe weitzman, andypost, dcam: Fixed fallback in drupal_get_hash_salt(), move it to bootstrap.inc, use instead of $GLOBALS['drupal_hash_salt()'].

Issue #1605040 by TravisCarden, mitron | EdgarPE: Fixed drupal_send_headers() ignores headers with valid but falsy values.