Modernise VeloSim code
- Add
final
keywords to component classes - Add missing
override
keywords - Prefer implicitly generated destructors over explicit trivial destructors
- Initialise member data at declaration
- Fix untested StatusCode in Error and Warning calls
- Prefer Error() to error()
- Hide all warnings from Boost, ROOT and CLHEP (see gaudi/Gaudi!205 (merged) and gaudi/Gaudi!192 (merged))