Issue #2045927 by herom, martin107, ianthomas_uk, Xano, michaellander, Sutharsan: Replace all drupal_alter() deprecated function calls.

Issue #1165694 by pillarsdotnet, Sutharsan, droplet: Remove default nomask from file_scan_directory().

Issue #2121849 by moshe weitzman: Move chmod.directory and chmod.file out of config and into settings so that file writes are independant of the config system.

Temporary rollback since it conflicts with a critical issue.

This reverts commit ce08ea73.

Issue #2099205 by Wim Leers, zero2one, Gábor Hojtsy: When uploading and inserting an image trough the WYSIWYG plugin a relative path should be used for the image source (src) .

Issue #2084535 by mErilainen, tankerjoe, DanielFbrg: Fix file_copy documentation around the case when source and destination are the same

Issue #2099467 by moshe weitzman, chx: Let non-interactive installers determine mode of files directory and its subdirectories.

Issue #2089351 by thedavidmeister, meba: Convert all calls to check_plain() in core to Drupal\Component\Utility\String::checkPlain() in core/includes.

Issue #2100329 by cosmicdreams: Use \Drupal instead of Drupal to make IDEs and static code analyse tools happy.

Issue #1856766 by chx, Berdir, heyrocker, kim.pepper: Convert file_public_path() to the new settings system (make it not configurable via UI or YAML).

Issue #2045923 by drupalrv, tim.plunkett: Replace all module_invoke_all() deprecated function calls in procedural code.

Issue #1201024 by pillarsdotnet, jbrown, tim.plunket: drupal_realpath() should describe when it should be used.

Issue #2045189 by jlindsey15: Move file entity dependent code in includes/file.inc and system.module to file.module.

Issue #1987712 by dawehner, claudiu.cristea, damiankloip, andypost: Convert file_download() to a new style controller.

Issue #1984378 by aroq, JacobSanford:  argument is name of form field used to upload file, not 'filepath or URI of the uploaded file'.

Issue #625958 by slashrsm, quicksketch, eojthebrave, droplet, danlinn, czigor: Support Uploading Multiple Files for HTML5 Browsers via #multiple attribute.

Issue #1561362 by Niklas Fiekas, chrisdolby, mtift: Change file_transfer() to use BinaryFileResponse.

Issue #1049050 by mfb, TwoD, David_Rothstein, jpsoto: Fixed file_stream_wrapper_uri_normalize(): remove dead code.

Issue #1068266 by jbrown: Followup to drupal_mkdir() does not set permissions to directories it created recursively - fix directory separator issue affecting windows.

Issue #1068266 by linclark, andyceo, scottrigby, chx, jbrown, ñull, weboide: Fixed drupal_mkdir() does not set permissions to directories it created recursively .

Issue #1496480 by mrf, disasm, kbasarab, pfrenssen, cam8001, typhonius, Letharion, ACF, vijaycs85, heyrocker, Berdir, alexpott: Convert file system settings to the new configuration system.

Issue #1356170 by ohnobinki, tim.plunkett: Remove all uses of array_merge_recursive(), or document why they are being used instead of NestedArray::mergeDeep().

Issue #1874612 by plopesc: Simplify file.inc by file_stream_wrapper_valid_scheme()(FALSE) return FALSE.

Issue #1874342 by erikwebb: Fixed Undefined constant STEAM_WRAPPERS_LOCAL used in file_get_stream_wrappers() documentation.