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

- Add test which reads a "default"-pet file and writes it out and then compares them
- Detect differences in reading/writing/overall file format
- fix: ColorMarker read in saturation for value

- Reads in whole intrinsic calibration at once
 -> reads in reprojection error without setting it to NaN later on

- Also add -autoIntrinsic documentation

- Crash due to comparison of cv::Mat with different size
- Append zeros to old model such that it has the same size as the new one

- Move "filter before" GroupBox into own widget
- Move "intrinsic" GroupBox into own widget
- Save intrinsic calibration in struct
- Use said struct as parameter for `CalibFilter`
- Add `setValue`-helper function for loading values into UI respecting min/max
- Move PeTrack-Version from Setter to Constructor of Petrack-object
- Add Unit-Tests

- Fixed boolean expression with inverted button
- Refactored boolean expression for better readability