Add missing @Override annotations to almost everything

This is the same idea as commit efe69542f4b3439ace8cd7fa14c37f8a5914a199
on master branch, see its description for how it was done.
It was done again manually instead of cherry-picking the commit: This
branch here is a fork based upon build0013, so it is behind master over
1000 commits. Merging the commit from master would have been a lot more
work.

The @Override annoations were auto-added based upon the interfaces
provided by fred build01466. This is before purge-db4o. The purpose of
this branch here is to make WOT compile against purge-db4o
(testing-build-1467-pre1), and some fred functions are removed there. So
its a good idea to add the missing @Override of the old interfaces: Then
the compiler will complain about overriden functions which have no
existing parent interface in purge-db4o anymore.