MDL-27764 restore - always restore as much info as possible (1.9 approach)
In 2.0 we had reduced the types of restore operations where we allow
to load the section names and section descriptions, only proceeding
when restoring to new course or to existing course, deleting.
With this patch, we change to the old 1.9 way, that was to restore
the section information always, no matter of the type of restore
operation (course restore, import, to new or to existing course,
deleting or adding). The only exception is that it's always checked that
the target section names and descriptions are empty.