MDL-44065 Course: _add_instance exception leads to inconsistent db

If an exception occurs during a module's _add_instance function, this
results in a course_modules entry with instance=0. The system already
handled returning false to this function, but did not handle
exceptions.
MDL-43930 assign: Do not log when user is logged in as someone else.

I do not agree with this behaviour - but this makes it consistent with other modules.
MDL-44272 events: Fix incorrect urls in course module events
MDL-44361 Import YUI 3.15.0

Includes @VERSION@ fix
MDL-44361 Javascript: Fix js_pending injector Y.io

The previous (slightly whacky) way that we were doing this in previous
versions is no longer supported (and was arguably only supported by being
buggy).

The correct way of doing this is to use a trigger.
MDL-32917 port YUI2 Moodle calendar into a shifted YUI3 Calendar
MDL-41248 completion: fix non-translatable text.

There were two hard-coded strings. Thanks to Guido Hornig for the suggested fix.
MDL-44278 Quiz time overrides: use the same step everywhere.

On the main form, you could select to the nearest minute. On
the override form you could only select to the nearest 5 minutes.
MDL-44074 theme_bootstrapbase: No 768px-979px & 1200px+ empty blk span calcs.
MDL-44180 mod_quiz: unified @package use
MDL-44436 context: Context IDs are forced to be int

The method context::insert_context_record() sets the context::$id to
an int, while when we create an instance, the $id is often read from
a DB $record object, and is a string. The ID should always be an int.
Merge branch 'MDL-32917-master-nomerge2' of git://github.com/mouneyrac/moodle
Merge branch 'MDL-44436-master' of git://github.com/FMCorz/moodle
MDL-43468 mod_assign: Webservice parameters were not safely cleaned
MDL-44321 unittest correction since snapshot is not a reference to object any more.
Merge branch 'wip-MDL-44321-master-fix' of git://github.com/marinaglancy/moodle
Merge branch 'MDL-44278' of git://github.com/timhunt/moodle
MDL-41266 Logging: Added choose option for external database store
Merge branch 'MDL-44272-master' of git://github.com/ankitagarwal/moodle
Merge branch 'wip-mdl-41266' of https://github.com/rajeshtaneja/moodle