MDL-45764 mod_lti: Fix adding General Tool

This error only occurs when a ltisource
plugin is present that implements the
get_types callback.
MDL-38693 themes: amended z-indexes

Amended #dock z-index level from 11000 to 5000 across all themes; amended z-index style of #page-header in Overlay theme such that elements no longer occlude TinyMCE.
MDL-10115 User profile: Allow full list of courses to be viewed on a user's profile
MDL-10115 User profile: Use moodle_url and html_writer::link for course links on user profiles
MDL-41258 Forum: Add additional unit tests for forum digest settings
MDL-45721 core_backup: only trigger the course_restored event when restoring a course
MDL-45652 core_backup: display warning on restore destination form when necessary data is missing
MDL-45933 Assign: Prevent fatal error when there are no users in the grading table
MDL-39883 events: Create a new api create_from_cm for module create event
MDL-39883 events: Trigger a module created event when duplicating a module
MDL-44512 themes: fix for custom menu submenu arrows on RTL languages
MDL-46035 mod_survey: a string change to make an error message always correct
 MDL-45044 filter_tex: properly escape excutable pathnames for Windows
MDL-46076 Lib: Allow javascript-static.js to somewhat work in IE7 [2.6]
MDL-46079 Restore: Can run out of memory in get_records call
Automatically generated installer lang files
MDL-37145 caching: noted recommendation for dedicated memcache servers

Several reports have been made about the unexpected purging of entire
memcached servers when MUC is configured to use Memcache and caches
get purged.
This is expected and occurs because the memcache extenions don't
provide isolated containers. Moodle data is stored along side any other
data in the cache and when caches get purged all data gets removed
whether it belongs to Moodle or not.

The docs cover this point and here I've added notes about this to both
config-dist.php and cache/README.md
MDL-41746 External api: Allow multiple calls to validate_context at different levels

(Only from webservices)
Merge branch 'MDL-38693-26' of git://github.com/jethac/moodle into MOODLE_26_STABLE
Merge branch '37145-26' of git://github.com/samhemelryk/moodle into MOODLE_26_STABLE