MDL-25012 blogs: Remove bloglevelupgrade tool

This was used for 1.9->2.x upgrade and is not longer relevant.
MDL-25012 - blogs: introduce a specific 'enabled' config setting

Rather than overloading the $CFG->bloglevel setting which had a
confusing UI in the appearance subsystem.

In order to achieve this we modify take the defaults from the existing
bloglevel setting and set that for $CFG->enableblogs. Note that in order
to prevent a bad default settings from being set we also set
$CFG->bloglevel to a valid 'enabled' setting.
MDL-25012 - blogs: only show the settings page when blogs enabled
MDL-34745 mod_forum: remove throttlingapplies string

Its no longer used
MDL-29192 - clarify email_to_user call
MDL-34543 mod_assign Fixing problem where previous feedback does not populate when you re-enter the grading view. add_plugin_grade_elements() was expecting grade object, but was being given grade string.
MDL-33640 - Add ability to use custom filepicker templates

Allow repository plugins to register a template by defining a get_template() method, coupled with the ability to request the template be used by create_upload_form() instead of the standard 'uploadform' template.  The template is automatically registered using the plugin's name, and core templates will override any which clash; this also means that a theme can override these templates in a custom renderer if it wants to.
MDL-34783 Retrieve the sectioncache parameter for enrolled courses in the course_overview block

The sectioncache field is used by course_modinfo and without it, the
modinfo cache is repeatedly reset.
MDL-34376 mod_assign Omit assigns with no due date from print_overview.

Modify assign_print_overview to omit assigns that have no due date set, in line with behaviour
in 2.2 and other tools.
MDL-33640 - change $templatesinitialized to an array; improve naming and automate use of template

* $templatesinitialized is now an array, so that subsequent calls to initialise_filepicker which request different repositories will include those (and only those) templates which it requires but have not yet been included
* The get_template method has also been renamed to get_upload_template (and the template to "uploadform_" followed by the repository type), since it only applies to upload forms
* If a plugin provides a get_upload_template method, the template it returns will now automatically be used instead of the standard uploadform template when generating an upload form
MDL-34820 theme_afterburner: adjusted style/pagelayout.css to add 2% to width in .side-pre-only #region-main
Automatically generated installer lang files
MDL-33531 Fixed the regexp to find old backup files, considering backup_shortname backup option
MDL-33531 backup Avoiding possible Notice
MDL-33531 backup Added format_string to course shortname
MDL-25347 blog Checking association capability at course and module levels instead of system level
MDL-32344 blog Adding a renderer to manage entries output
MDL-34820 theme_afterburner: adjusted value in style/pagelayout.css for.side-pre-only #region-pre-box
MDL-34337 scorm: Updating export of basic reports as csv, to use new csv exporter class
MDL-34336 scorm: Updating export of interaction reports as csv, to use new csv exporter class