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-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-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
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-34782 detect code abusing integer limits in mysql database

It is allowed to store only ranges specified in install.xml, for integers it means number of digits specified in size.
Automatically generated installer lang files
MDL-34593: Plagiarism API - add extra plgin param to get_form_elements_module
MDL-34862 question preview: improve preview ownership check.

Users should only be able to access their own quetion preview. In the
past, for reasons I can no longer remember, this was enforced
using the session. It is much better to set the question_usage to belong
to the user's context.
MDL-22773 Database module export: include internal fields

Fields included:
 * User details (fullname, username, email)
 * Time added/modified
 * Approval status
MDL-34885 phpunit: better cygwin detection.

For some reason, on my computer, $_SERVER['SHELL'] was not set, so I
changed the test to also consider $_SERVER['TERM']. This now works for
me.
Merge branch 'MDL-34783-master-1' of git://git.luns.net.uk/moodle