CheckIO: Improved handling of function return type
simplifyCalculations: Improved handling of casts (#4899)
Fixed Function::retDef initialization:
- Move/Copy Constructors and Destructors do not have a return type neither
- Fixed crash in SymbolDatabase::printOut
- Added testing
Fixed false positive #5004
Refactorization: Make use of Function::retDef where it makes sense
Test GetShowErrorMessages in testcmdlineparser.cpp
Fixed #4899 (False positive on unused variable)