Modernize MCEvent

• add initializers to member declarations and make default constructors = default
• add [[nodiscard]] where appropriate
• add some const
• have setters take their argument by value, and then std::move to the destination
• have setters return *this (instead of void) to allow daisy-chaining
• remove redundant protected declarations
• remove redundant inline declarations
• remove redundant destructors
• prefer STL algorithms over raw loops
• prefer range-based for loops
• prefer auto instead of ...::iterator
• remove pragmas specific to Intel compiler
• prefer using over typedef
• remove x bit from header files

must be applied in conjunction with Lbcom!414 (merged) and Boole!254 (merged)