Resolve "First TrackPoint is always drawn black (instead of green/blue)"

The black circle is using the default color of the pen, since we first assigned the pen and then changed the color. Therefore, switching the order, first changing the color, fixes the problem.

Closes #422 (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()