Get rid of referencelastsync and referencelifetime from the {files} table

You must have existing shortcuts to internal and external repositories before upgrade. Before test hack the code in repository/lib.php and change value returned by get_reference_file_lifetime() to something small (i.e. 30 seconds). Note that filesystem repo overwrites it. Test for regressions/errors in the following operations: If you had shortcuts before the upgrade, make sure they still work. Add a file from repository as a copy and as a shortcut (both image and non-image files, in both filemanager and text editor) Create a file resource with shortcut to some external repository, make sure to check the option "display size" Replace the files in the repositories Make sure the image thumbnail and file size for non-image files is updated for the shortcuts (you'll have to wait for 30s or whatever you have hacked to above) Create several shortcuts to the same file in internal repository (private files, server files) Overwrite the source file of those shortcuts, make sure the shortcuts are updated immediately Delete the source of those shortcuts, make sure they are converted to the normal files. Please don't report UI bugs already reported in MDL-41491 and MDL-41591