MDL-25031, MDL-25198 fixed use of proper table prefixes in blocks upgrade and fixed invalid DML call in questions ugprade

There was a mistake in the text format upgrade in the question bank. The wrong conversions were performed, and the wrong arguments were passed to text_to_html in the conversions that were done.

Also, not all the calls to format_text had been updated to use the values in the new format columns.

I think this change fixes everything, but I have only had very limited time to test it. I am committing it anyway, because that seems to me to be the best way to maximise testing. I think that the new code is certainly better than the old code was.

AMOS BEGIN
 MOV [move scheduledsetup,core_backup],[automatedsetup,core_backup]
 MOV [scheduledsettings,core_backup],[automatedsettings,core_backup]
 MOV [scheduledstorage,core_backup],[automatedstorage,core_backup]
 MOV [scheduledstoragehelp,core_backup],[automatedstoragehelp,core_backup]
 MOV [scheduledbackupsinactive,core],[automatedbackupsinactive,core_backup]
 MOV [scheduledbackupstatus,core],[automatedbackupstatus,core_backup]
 CPY [schedule,core],[automatedbackupschedule,core_backup]
 MOV [backupschedulehelp,core],[automatedbackupschedulehelp,core_backup]
AMOS END

pagetypepattern can not be null, so we ignore these until we find a way to fix them properly, sorry

message MDL-24694 removed references to user->emailstop. the column itself will be removed in a later version

I forgot to unset the $CFG->emoticon from the memory so the upgrade
process still had the old emoticons format loaded in the memory which
led to coding exception.

blogs MDL-24875 Increased uniquehash field size to 255 and added a str length check to external blog syncing.

MDL-24694 fixing broken upgrade once more - this step was skipped because two blocks had the same version number

- added message provider to manage assignment's messaging
- user_preferences.name length changed form 50 to 255 due to long messaging preference names.

MDL-24772 fixed a theoritical problem with sites that do not have any enrollable roles with moodle/course:view, credit goes to Tim Lock

registration MDL-24641 get language code from the full language list codes, not from the Moodle language package code

MDL-24302 removing multiple field from block table in install.xml - it was already removed in upgrade once

* handlers can be defined as internal or external
* external handlers are not called instantly when inside DB transaction
* code cleanup
* more robust detection of broken handlers
* refixed unit tests
* removing all pending events from 1.9 - these can not be processed due to encoding changes
* finally using real 'component' in handlers table

blocks upgrade MDL-22693 We also need to drop another old index, on sites that were upgraded from 1.9

community hub MDL-24215 change the site secret key for get_site_identifier in the registration process => increase the DB field size + change the confirmation form to the get_site_identifier TEXT format

MDL-24116 dropping tables that were used in old xmldb test suite, the tests will be moved to functional db tests in subsequent commits

blocks upgrade MDL-22693 Forgot to change the precision of the block_instances.pagetypepattern column to 64 chars. Do it now.
You have to drop and re-create the associated index, otherwise this will not work, at least on Postgres.

MDL-23885 flattening filepool directory structure - hopefully this will lower the number of directories but still keep a reasonable number of files in each directory on large installs; see tracker for more details

MDL-22001 filter_text() and filter_string() now use context parameter instead of courseid, PAGE->context is used only as a fallback; moved comment stuff away from format_text() because it does not belong there; filterlib is not using courseid except for legacy filters; fixed coding style in filters;Êimproved php docs; fixed upgrade of filters (should be in plugins, not core)