MDL-41593 admin: use default setting if preventexecpath active

This resolves problems when installing Moodle
and addons when preventexecpath active.

Please note the admin_setting_configfile is still
incorrectly restricted - this will be resolved by
MDL-40949.
MDL-47555 core_availability: Issue with page layout & grade restriction

* Set pagelayout before getting section info, otherwise conditional activity renderers will default to the default 'base' layout.
MDL-38065 gradebook: Fix issue with hidden categories breaking rowspan.

Hidden subcategories break the rowspan in the gradebook; this fix corrects
the calculation of the rowspan.
MDL-38172 Lesson: Additional Info not displayed at end of lesson
MDL-47684 mod: better validation of rating options
MDL-47752 grading: fixed bugs with the modgrade element
MDL-46499 navigation: better enrolled course limit

We now user $CFG->navcourselimit to limit the number of
courses shown in the navigation when browsing another users
full profile. Previously it showed all courses which caused
some slowdown.
MDL-47077 report_participation: fixed pagination in groups
MDL-47754 install: fix redirect loop
Merge branch 'MDL-38065-fix-27' of git://github.com/jmarthaler/moodle into MOODLE_27_STABLE
MDL-46332 : Display of 'Remove' button in Add/Remove Groups in Grouping

Fixed styling of Add/Remove Groups in Grouping to now use the same
layout as the Group Members page.
This fixes the issue with buttons being unaligned and introduces
consistency between pages.
Merge branch 'wip_MDL-47754_m27_installredir' of git://github.com/skodak/moodle into MOODLE_27_STABLE
MDL-47340 action_menu: selector, RTL, consistency fixes
MDL-47651 quiz responses: allow for qtypes without responses
MDL-47666 DB auth & enrol: unit tests fail with custom DB drivers

Changed to used $DB->get_db_family, rather than hard-coding the list of
class names.
MDL-47673 quiz generator: default grade 100 & fix review options

The review option defaults need to be like what you get from the editing
form, no what is stored in the database, or they don't work!
MDL-47711 behat: make it easier to copy the init.php command.
MDL-47726 availability: fix tests when there is a text custom field

This unit tests assumed that on a fresh install, there were no custom
user-profile fields. Given some third-party plugins, that assumption is
false.
Merge branch 'MDL-47673_27' of git://github.com/timhunt/moodle into MOODLE_27_STABLE
Merge branch 'MDL-47726_27' of git://github.com/timhunt/moodle into MOODLE_27_STABLE