port LHCb MT developments to Gaudi master

among others we have
- `Gaudi::Functional`: base classes to write algorithms as pure functions
- `AnyDataWrapper`/`AnyDataHandle`: helper to store any type in the Transient Store (DataSvc)
- fixes to `DataObjectHandle`
- fixes to `GaudiHive`
- new tests and examples
- modernization (removed empty destructors, ...)

See merge request !245