Qt: Use AssetsAssetReader to load Qt assets.
Qt: zlib is already used by Qt. Only compile it for exotic Qt builds where 'no-zlib' is configured. We will need to link it manually if 'system-zlib' is configured. Otherwise we already have it.
Qt: Update menubar action code. Make it more readable.
Qt: Load the language too, if detected on boot.
Qt: Allow building project from any directory. #4605
Qt: Show window before expanding widget. Fixes #4608
Qt: Cleanup the menu creation even more. Use classes instead of defines. Now automatically translates and sets state. Update translations.
Qt: Put all resources in to the binary. The app should be standalone now. Also fixes #4615
Buildfix for older compilers, such as GCC 4.6.3