MDL-37431 question preview: cron performance problem.

This query was performing badly. The solution seems to be to add a
redundant JOIN and WHERE to the subquery.

I renamed the table aliases in the subquery to avoid name collisions
elsewhere. I am afraid that makes the diff rather unhelpful. The
    AND subq_qu.component = :qubacomponent2
line is new. The other lines have just had subq_ added.
MDL-37485 plugins overview: require_login before _capability.
Moodle release 2.3.4
MDL-31616 block editing: show in subcontexts does not work on category pages.

Thanks to Ian David Wild for pointing to the proper fix.
Merge branch 'wip-mdl-35780-m23' of git://github.com/rajeshtaneja/moodle into MOODLE_23_STABLE
Merge branch 'MDL-37397-m23' of git://github.com/andrewnicols/moodle into MOODLE_23_STABLE
Merge branch 'wip-MDL-36335-23' of git://github.com/abgreeve/moodle into MOODLE_23_STABLE
Merge branch 'MDL-36511-23' of git://github.com/srynot4sale/moodle into MOODLE_23_STABLE
Merge branch 'MDL-36095-m23' of git://github.com/sammarshallou/moodle into MOODLE_23_STABLE
Merge branch 'wip-MDL-35885-stable23' of git://github.com/phalacee/moodle into MOODLE_23_STABLE
MDL-35568 course dndupload - resources created with the same visibility as the section they are dragged onto
Merge branch 'MDL-37048-m23' of git://github.com/ankitagarwal/moodle into MOODLE_23_STABLE
MDL-35818 - Enrolment - Changing all enrolment method icon alt text attributes to include the name of the course
MDL-15930 - admin: reorganize logic to allow ->fullnamedisplay to be used as default sort.
Merge branch 'wip-mdl-29534-m23' of git://github.com/rajeshtaneja/moodle into MOODLE_23_STABLE
MDL-30797 backup: Use correct API call for mapping groups to groupings on import/restore
MDL-30797 - backup groups: Added a parameter to the groups_assign_grouping function.

$timeadded has now been included so that the backup / restore functions can now use
this API rather than duplicating the code.
Merge branch 'wip-MDL-30797-23' of git://github.com/abgreeve/moodle into MOODLE_23_STABLE
MDL-36674 Administration: out_as_local_url will check for both http and https url's

out_as_local_url will first check if url passed in wwwroot, if it's not then it will check
if loginhttps is enabled and url is httpswwwroot
Merge branch 'MDL-37378_23' of git://github.com/timhunt/moodle into MOODLE_23_STABLE