Fixed #4617 (False positive (style): noexcept for constructors)
Fixed #4539 (False positive: Possible null pointer dereference)
Fixed #4624 (Wrong error for instances of std::unique_lock (variable is never used))
Changed behaviour of Token::is*Op() functions:
- Rename Token::isOp() to Token::isConstOp() (indicating that the operator does _not_ modify the input variables)
- Create new Token::isOp(), returning true also for ++, -- and assignment operators
- Make Token::isExtendedOp() returning also true for all assignment and ++/-- operators
Fixed MSVC warning - removed unused variable/function declaration.