Eloy Lafuente authored Jun 14, 2017 and Dan Poltawski committed Jul 10, 2017

This just deletes all the upgrade steps previous to 3.0.0. Some
small adjustments, like adding missing MOODLE_INTERNAL or tweaking
globals can also be applied when needed.

Also includes an upgrade step to prevent upgrading from any
version < 2015111600 (v3.0.0) as anti-cheating measure.

Next commit will get rid of/deprecate all the upgradelib functions
not used anymore in codebase.

This just deletes all the upgrade steps previous to 2.7.0. Some
small adjustments, like adding missing MOODLE_INTERNAL or tweaking
globals can also be applied when needed.

Next commit will get rid of/deprecate all the upgradelib functions
not used anymore in codebase.

MDL-23068 removing obsolete $result and removing empty upgrade files that would be probably never used at all + minor cleanup/fixing

MDL-22950 adding new component column to the files table, unfortunately this change requires changes in all 2.0dev code, please review all custom code that was already upgraded to 2.0; fixing multiple problems and regressions in mod/assignment

MDL-22548, added sortorder field to files table, drop mainfile field from resource table, use sortorder to decide main file

MDL-20065 new implementation of File module, modules sub-types are being migrated to separate modules; remaining issues to be listed as sub-tasks in tracker

MDL-16002 rewritten upgrade locking and better upgrade progress tracking; MDL-16070 Do not use $a[0] syntax in lang packs + various other upgrade improvements and fixes

MDL-15246 moving all remaining ddl function to adminlib, keeping old lib/ddllib.php only for BC withexisting code; fixed inline docs related to ddl

Merged from MOODLE_18_STABLE