Cleanup QList usage and some stuff

@antis81, could you have a short look over this. It does:

- Move all libGitWrap object forward declarations into a central place in GitWrap.hpp
- Changes all remaining usages of QList with QVector
- Does proper typedef declarations for all Lists
- Makes qDebug() macros published code instead of inline
- Do Qt-Includes centraly (the ones we need for API in GitWrap.hpp, most others privately in .cpp)
- Doesn't include <QDebug> in a global scope (early on). Most of our code doesn't use QDebug and where we do, we can as well include it explicitly.