MDL-33536 navigation: hide hidden categories from the navbar

Conflicts:
	lib/navigationlib.php
MDL-42723: Hide and handle LDAP error when user not in context being checked

MDL-41304 only fixed the case when 'Search subcontext' is enabled. We need to
fix the case when it's not enabled too.

While silencing errors with an @ should be avoided if possible, there's no
other way to prevent the warnings in this case.
MDL-42672 blocks: warnings on /mod/xxx/index.php for frontpage course
MDL-38574 qtype chooser: quick fix to make it fit on-screen.

MDL-32729 will provide a better fix for this, but we may as well apply
this quick fix on stable branches.
MDL-42598 quiz variant randomisation not random enough.

A student would get the same question variants (for example for a
calculated question) on their first attempt at both copies of a
duplicated quiz.
Automatically generated installer lang files
MDL-42839 MUC: Memcache server configuration too sensitive to whitespace
Merge branch 'wip-MDL-42672-m24' of git://github.com/marinaglancy/moodle into MOODLE_24_STABLE
Merge branch 'wip_24_mdl-42723' of https://github.com/iarenaza/moodle into MOODLE_24_STABLE
Merge branch 'MDL-38574_24' of git://github.com/timhunt/moodle into MOODLE_24_STABLE
Merge branch 'MDL-42839-m24' of git://github.com/sammarshallou/moodle into MOODLE_24_STABLE
Automatically generated installer lang files
MDL-33536 Navigation: Add missing require_once for safety.
Merge branch 'MDL-33536-24' of git://github.com/damyon/moodle into MOODLE_24_STABLE
Merge branch 'MDL-42598_24' of git://github.com/timhunt/moodle into MOODLE_24_STABLE
Automatically generated installer lang files
MDL-42912 glossary: oracle-compatibility of SQL queries
Merge branch 'wip-MDL-42912-m24' of git://github.com/marinaglancy/moodle into MOODLE_24_STABLE
MDL-42912 mod_glossary: Fix typo and call to core_text
Merge branch 'install_24_STABLE' of git://git.moodle.org/moodle-install into MOODLE_24_STABLE