MDL-38267 assign: No Submit button after cut-off date

Conflicts:

	mod/assign/locallib.php
	mod/assign/tests/locallib_test.php
MDL-41595 mod_book: Book mod does not add TOC to default region
Merge branch 'MDL-38267-24' of git://github.com/damyon/moodle into MOODLE_24_STABLE
MDL-41534 theme: Missed backporting a style to hide empty table rows
MDL-37804 assign: Return proper notice when submissions closed.

MDL-38267 was returning the html page when it should have been adding to the list
of notices and returing false.

Conflicts:

	mod/assign/locallib.php
MDL-27684 repository: make require_login() throws exception instead of redirect
weekly release 2.4.6+
MDL-29987 File resource: fix problem with PDF display on mobile devices

Setting the default display option for PDF files from DISPLAY_EMBED to DISPLAY_OPEN
MDL-38317 grade import: Translation support for import mappings form.
MDL-38194 Files: Allow download of large backup files

The PHP readfile function does not work for files more than 2GB.
This commit provides a wrapper that can be used so that files less
than 2GB are sent with readfile, and files larger than 2GB are
sent manually.

The change applies to all uses of pluginfile.php, although in
reality, backup files are probably the only ones likely to be more
than two gigabytes.
Merge branch 'MDL-41534-24' of git://github.com/damyon/moodle into MOODLE_24_STABLE
Merge branch 'MDL-29987_24' of https://github.com/bostelm/moodle into MOODLE_24_STABLE
MDL-37524 SCORM: mode not calculated correctly.
Merge branch 'wip-MDL-27684-MOODLE_24_STABLE' of git://github.com/satrun77/moodle into MOODLE_24_STABLE
Merge branch 'm24_MDL-37524' of git://github.com/danmarsden/moodle into MOODLE_24_STABLE
Merge branch 'MDL-38194-m24' of git://github.com/sammarshallou/moodle into MOODLE_24_STABLE
Merge branch 'MDL-38317-moodle24' of git://github.com/StudiUM/moodle into MOODLE_24_STABLE
Merge branch 'MDL-41595_M24' of git://github.com/lazydaisy/moodle into MOODLE_24_STABLE