moving the "Coordinate System" box out of control into its own cpp/h/ui file

- that means moving the widget and all its signal/slot connections
- Create new interface `WorldImageCorrespondence` for all calculations between image/pixel coords and world coords (dispatches to `ExtrCalibration` when 3D, else uses old 2D coord sys)
- Moves the methods for wold image correspondence from the `ImageItem` to the newly created `CoordinateSystemBox`
- During this change: Make the 2D coord system not depend on `mapToItem`; its now using normal affine transformations (`QTransform`) instead, which incidentally should make #383 easier
- `imageSizeChanged` is now a slot of `Control`, such that `ImageItem` can call it without having a reference to `Control` by sending a signal (Following that: image item is now now directly depending on control anymore)
- Some include clean-up