Cleanup and prepare for 2.7
General overhaul w.r.t. version 2.7 specific changes of the core modules, and s.t. code compiles without warnings.
Further cleanup may be part of a follow-up MR.
General overhaul w.r.t. version 2.7 specific changes of the core modules, and s.t. code compiles without warnings.
Further cleanup may be part of a follow-up MR.