Use struct instead of class for forward declarations if the object is defined
as struct.
Remove unused data members, variables and parameters.
Remove an explicite usage of std::move to allow copy ellision.
Correct type in printf statements.
Add missing virtual destructor in some class.
Fix two issues where closing braces were at the wrong place.

L1: add consistency checkers for L1Parameters, L1Station, L1UMeasurementInfo, L1XYMeasurementInfo, L1MaterialInfo, L1Material, L1FieldSlice, L1FieldRegion, L1FieldValue classes