Use std::unique_ptr<T> instead of raw pointer where applicable about librepcb

[ubruhin]

Until now, Qt's smart pointers are used instead of the C++11 ones. The only disadvantage seems to be that QScopedPointer has no move semantics. As a workaround we could use QSharedPointer where move semantics were required.

The other way would be to replace all Qt smart pointers with C++11 ones and don't use Qt pointers any more.

C++11 smart pointers never throw std::exceptions by themself, do they? If they do, we would have to wrap them with our own exception classes...

[ubruhin]

I consider this as closed for following reasons:

• C++ smart pointers can throw exceptions in many situations. So we would have to wrap all std::exception with our own librepcb::Exception class. This is PITA.
• Qt's smart pointers are already widely used in LibrePCB. And in every new class I'm creating or refactoring, I use smart pointers instead of raw pointers where applicable.
• Replacing all old raw pointers with smart pointers at once would require lot of effort. I think it's better to replace them step by step when refactoring old classes. Most of the classes will need some refactoring anyway at some point...
• Using smart pointers is now recommended in the developers documentation.
• Maybe Qt provides a unique pointer with move semantics someday ;) Until then we can use QSharedPointer instead.