MDL-46416 group: Use a revision number for group pictures
MDL-48064 atto_editor: Check if activeElement is child node in isActive
MDL-35494 core_backup: fixed activity restoration issue
MDL-47601 core_backup: ensure removal of automated backups
MDL-48246 theme: Fixed typo in 'hidepanelicon'

Conflicts:

    theme/bootstrapbase/style/moodle.css
MDL-48064 atto_editor: Expand event subscription for saving selection
MDL-38343 cache: better test server strings
MDL-23912 core_comment: update count after deletion
MDL-48265 feedback: Added alt text to ghostscript test image
MDL-48252 scheduled tasks: file_temp_cleanup_task does full delete.

This scheduled task was previously only doing a partial delete
due to the fact that the directory modification time would be
updated when a child file was deleted. It would then have to
wait another week before that directory could be deleted.
MDL-46534 course: Remove calls to error_log in activity duplication
MDL-45867 atto_equation: Change preview update to asynchronous
MDL-23839 navigation: Check for assignable course category roles
MDL-22043 mod_forum: Fix toggle subscription editing button behaviour

Update the user session property before generating the button which relies
upon it.
MDL-48276 qformat_xhtml: avoid uncessary html in .css file

In order to help automated tools move the html out of the css
file.
MDL-48277 css: initial csslint config file
MDL-47832 cache: removed data source aggregate functionality

Cache data source aggregate functionality was found to be broken
and unused, because of this the decision was made to remove it
rather than fix it.
As it was broken we did not follow typical deprecation methods and
instead the code was removed outright with only structure
remaining and left deprecated.
MDL-48252 scheduled tasks: Unit test for file_temp_cleanup_task.
MDL-48304 moodle_url: compare now considers anchor
MDL-47329 mod_book: use embedded pagetype instead of hardcoded HTML