Due to a mistake in !267, the error of the extrinsic calibration was calculated using the old calibration (i.e. all zeros on a new project). This leads to a terrible error and thusly to the rejection of the new calibration.

This commit fixes this by using the new extrinsic parameters to calculate the reprojection error. It also adds some simple regression tests for the extrinsic calibration to catch such mistakes earlier in the future.

- Add PGroupBox
  Custom GroupBox with option to "gray out" its content
- Change all GrouBoxes in calibration tab to PGroupBox

Load AVG_PH instead of SUM_PH etc., since they are saved as such in the pet file

- Moves ui and code of AlignmentGridBox out of Control into its own class
- Changed GridItem to work with AlignmentGridBox instead of Control

This commit deletes the concurrent call to updateImage, since it lead to instability. Especially on Mac, PeTrack would randomly freeze and perform poorly overall; sometimes even crash. (Due to functions executed on different threads which should only be executed from a specific thread, potentially over a queued connection, i.e. signal-slot)

The Player continued to play the video after the main window was closed.
Now pauses the video once the window is closed, so that all of PeTrack
can exit.

- handle special case of calling the function without wanting to delete anything
  (i.e. cound == 0)

- delete dead code
- simplify existing code, e.g. by using Qt drawing utilities instead of our own

Allows to display the result of the current plausibility checks, e.g., inside ROI at begin or end, short trajectories, equality to other person or fast velocity variations, in a table. Clicking on the table jumps to the person(s) and frame of the failed check. A color encoded column shows if the issue was already resolved. The color will be automatically adjusted when a person is changed.

- 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

Remove the inheritance from `TrackPerson` in favor of composition, this allows a better handling of interactions with the `TrackPerson` as changes now go through defined interfaces.

Main changes:

* `TrackPerson` no longer **is** a `QList<TrackPoints>`
* `TrackPerson` now **has** a `QList<TrackPoints`
* new function `deleteFrameRange` which will delete a range of frames, but leaving no gaps in the middle
* `lastFrame` is now compute and not stored, hence no need to update it
* `firstFrame` is set when creating a `TrackPerson` and will be updated when needed automatically

The image center (or principal point) could be set wrongly if the previous project had a significantly lower resolution, disallowing values for cx,cy such as the correct ones for the next project.

-> load video (and therefore imagesize) first

New procedure for dealing with invalid pet-file:
- save current state before loading new file
- open new file
- throw exception on erroneous value
- catch exception at top level and restore old state
- show error message

- Delete some dead code in CoordItem
- Slightly refactor `paint`-method

- Introduces `ExtrinsicParameters`-Struct
- Extract `ExtrinsicBox` from `Control`

- Move slots to FilterBeforeBox when concerning its elemets
- Fix Tab order of new extracted widgets
- Delete dependency to Control by AutoCalib