MDL-41112 fix theme and js caching info in config-dist.php
MDL-41122: Trim on RSS body to prevent Remote RSS block from failing on valid feeds
MDL-41157 calendar: add unit tests for calendar_get_course_cached
MDL-41191 enrol: unit tests for enrol_get_shared_courses
MDL-27595 backup: allow course import with warnings
Proceed with import if warnings are found, but display the warnings afterwards
MDL-41036 Question category info should use HTML editor

This is a minimal fix. All this code could do with a clean-up, but at
the moment, it works, so I am not going to touch it.
MDL-41162 quiz view page: invalid HTML.

We were sometimes outputting nested p tags. Change the outer one to a
div.
MDL-36789 Quick course cache integrity check for deleted modules
MDL-38203 multianswer qtype: feedback pop-up should be constrained.

So that, when there is a lot of feedback, it is all visible.
MDL-32191 navigation: Add keys to module and block settings nav nodes
MDL-37393 SCORM: Fixed PHP Strict Standards errors with AICC packages
MDL-37393 SCORM: Fix existing AICC scoes to use correct parent/child relationships
MDL-41144 enrol_flatfile: ignore deleted users
MDL-39572: Fix existing tests and add more to demonstrate issue with sql_order_by_text()
MDL-39572: Fix sql_order_by_text() to use length argument correctly
MDL-41106 cache: several fixes for the session cache.

This issue makes several fixes for the session loader and the session store.
* maxsize argument now works for session caches.
* fixed performance hole when interation occurs frequently.
* fixed cache purge bug occuring when multiple caches are defined before being used.
* improved lastaccess handling.
MDL-40893 backup: cache question answers for performance

To constrain memory we only cache a single question's answers.
A quiz must display this many answers, so it will not result
in undue memory pressure.

We now match on the full answer text rather than the first 255
characters.  This removes the risk of matching questions with the
same start.
MDL-41196 Unit Tests: Add a phpmailer message sink
MDL-41106 Cleaning up expired elements in session cache store

- Always make sure the elements in cache are sorted so we need to remove only elements in the beginning of array
- Remove expired elements from session store to free memory
- Minor bug fixes

Conflicts:
	cache/stores/session/lib.php
	cache/stores/session/tests/session_test.php
MDL-41106 cache: tidied up several elements