MDL-40343 forum: indent less when mobile, nested

Changes the indenting of forum replies to be relative to the width of
the parent container, so the indent decreases as threads get nested
deeper. Also reduces the indent size automatically for smaller screen
sizes.
MDL-46219 assignment: delete files when resetting assign activities
MDL-45636 course_rest: changed modcontext to coursecontext
MDL-46088 Impossible to click on Atto in a Quiz in 'Secure' mode.
MDL-46088 Quiz: Prevent alert when clicking in editor in secure popup
MDL-46088 quiz secure window: further Atto JS fixes.
MDL-46987 report_participation: Count duplicate logs as 1

Some of the actions generate more then 1 event.
Example: forum post create generate:
- post_created and
- accessible_uploaded
events which  gets logged at the same time.
Count them as 1 action and not 2, as it is
single action and report should show 1 and not 2
MDL-47316 mod_forum: Fix course overview performance

 make more efficient use of mod_info cache by processing courses
 sequentially.

Change-Id: I03b808c8a7efc42879ec2689fbd2a9fe7a8f1103
MDL-46391 messages: Display search button under contact list.

Add search button to only Message navigation -> Contacts section.
MDL-46054 web_services: bug fix in core_user_get_users

Thanks to Mikko Rantanen for the patch
MDL-46054 web_services: wrong key in exception string
MDL-46054 web_services: Fixed invalid parameter definitions
MDL-46978 gradebook: Edit grade item changes visibility of category
MDL-47301 libraries: Update Typo3 to v4.7.19
MDL-47301 libraries: Patch Typo3 for Moodle's use
MDL-47474 Calendar export: Fix user id in authorization check
MDL-47303 libraries: import latest jQuery library and friends
MDL-47477 libraries: use smoothness theme for jquery ui
MDL-47484 atto_indent: Prevent loss of rangy markers in some cases
MDL-47298 libraries: Update password_compat to latest version