Online Help shortcut change + redirect to new docu

Changed the shortcut for online help to F1 so it doesn't collide with the shortcut for hiding controls. Also changed redirection to the old wiki to the new docu page.

Reviewer Checklist

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
• documentation updated (if applicable)

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()

Closes #382 (closed)