Sync with DSL Platform changes.

Weak cache fixes. Share an instance across repositories so that cache invalidation works.
Currently added class resolution (which is not ideal due to AOP) so that Weak cache can be still used inside transactions.
Should add cache resolution inside caches themselves, although that will make it dependant on database interface.
Alternativerly add a signature for transaction - so that that info can live outside of IDatabaseQuery.

Added PostgresException to catch errors from DB - since errors in Postgres roll back transaction thus making it invalid, catch specific exception so that retry is possible inside same transaction.
Exposed this exception as conflict to the outside world.
Domain pattern interface cleanup.

Typos fixed.
Obsolete signatures moved from interface project.
Major refactoring.

Rename core projects from NGS -> Revenj to reduce confusion.
DSL Platform should cope now with the new name.

TODO: generated models rebuild
TODO: tutorials fixes