Setting playback speed influences exported framerate in trajectory files

This MR separates the playback fps from the original sequence fps.
User can set the sequence fps via the file menu and it is shown in the window title.
Sequence fps and playback fps are exported now.

Closes #332 (closed)

Reviewer Checklist

Formatting

• the pre-build checks succeed

General code quality

• naming conventions are met (see .clang-tidy for detailed information)
• no static analyzer warnings in new code parts (e.g., use clang-tidy for checking)

General usability

• old versions of pet-files are still loadable

Only if changes in UI

• new elements are also saved and loaded from pet-file
• check if tab order is still correct
• all new SpinBoxes are promoted
• new keybindings added to Petrack::keyBindings()

added bug label

assigned to @l.dressen

@l.dressen

This MR was discussed at the user meeting today.

At the core, the issue is that the FPS in the UI is both, the playback FPS as well as the FPS of the sequence. For stuff like image sequences we would want to be able to set the playback FPS separately from the sequence FPS (and in the case of codec errors, it's nice to be able to do that for video as well).

So we came up with the following wishlist:

• Use the current FPS below the view as playback FPS
• Add a possibility to edit the sequence FPS via some dialogue accessible via the File-menu
• Add the sequence FPS to the title of the window, such that one knows what the current FPS is
• Use the sequence FPS instead of the playback FPS for export

added 3 commits

• 8b426cf6 - rename to playback fps + tooltip for fps label
• 3b9e6a69 - sequence fps editable via file menu + show in window title
• c0773a0e - export sequence fps + minor adjustments + formatting

Compare with previous version

marked this merge request as ready

changed title from Draft: Resolve "Setting playback speed influences exported framerate in trajectory files" to Setting playback speed influences exported framerate in trajectory files

changed the description

changed the description

added 1 commit

• 7086ad85 - reintroduce line separator, fixtest I guess

Compare with previous version

marked the checklist item reintroduce line separator as completed

marked the checklist item adjust demo pet files for regression tests as completed

Current design up for debate

added 1 commit

• aa189c85 - set sequence fps window default fps value, add tooltip

Compare with previous version

ready for review

Sequence FPS is not saved in pet-file.

Sequence FPS default for image sequences should still be the old one; not 0