MDL-38347 - Calendar - Fixing arrow output on Android devices
MDL-28124 admin/tool/customlang: Changed page layout from 'standard' to 'report'.
MDL-40204 theme_bootstrapbase & theme_clean: Fix RTL 3 column lyt with 1 blk.
MDL-39779 wiki module: fix the alignment for required label to display inline on mobile devices
MDL-39153 webservices: Provide alternative to passing contextids

As per our policy webservices should never have a required contextid, thuse providing a support for passing contextlevel and instanceid as parameters to the api
MDL-39153 libraries: role_unassign doesn't accept context as parameter. Fixing incorrect doc.
MDL-39760: mod_assign: Add few more callback methods.

Adds lock, unlock and release_to_draft. All of them accept single parameter -
an assign_submission record.
MDL-39044 - Course Completion - Replaceing strtolower with multibyte safe textlib::strtolower
MDL-40264 fix essay handling of zero-string response

Fixes an inappropriate behavior of the is_complete_response() function
for the Essay question type, which caused the string "0" to be
inappropriately marked as an incomplete response.

Also adds a set of unit tests for the Essay question type's
is_complete_response.
MDL-40250 phpunit: Add unit tests for core_files_external::upload()
MDL-40033 behat: Waiting until file manager is available
MDL-40130 Caching: let make_categories_list use the cache it makes
MDL-40258: Fixed invalid json string error in file-picker
MDL-34610 remove legacy IE CSS. It breaks form layout
MDL-38631 Fixed faulty add_category call, introduced in 758103
MDL-38631 link categories in My courses only when needed
MDL-40200 Administration: Return the invalid user message and stop there

To avoid adding duplicate code, 'invalid user' and 'user deleted' checks
have been merged together.
MDL-40255 theme_boxxie/theme_formfactor: Added block-region class to layout files to enable dnd file uploader to work.
MDL-40233 add proper cache invalidation on frontpage setting save
MDL-39701 prevent filters before finishing 2.5 upgrade

This prevents problems with unsigned integers in MySQL 5.5