* Replacing the static_cast with a dynamic_cast in 668adaacdf is a regression because it cannot be guaranteed that the linked object is a sketch.
In fact it can also be a shape binder which is explicitly allowed.
Forum: https://forum.freecadweb.org/viewtopic.php?f=19&t=74939
* Move initialization of some variables into the if-statement
* QString::indexOf() is now marked as [[nodiscard]]
* QApplication::fontMetrics() is deprecated, use the constructor of QFontMetricsF
* fix -Wunused-result
* fix -Wunused-but-set-variable
* QString::indexOf() is now marked as [[nodiscard]]
* Replace deprecated methods of QMessageBox
* QMouseEvent::globalPos() is deprecated, use globalPosition().toPoint()
* QWidget::enterEvent() requires a QEnterEvent as argument
* QLibraryInfo::location() is deprecated, use path()
* QVariant::Type is deprecated, use QMetaType::Type
* QVariant::canConvert(int) is deprecated, use QVariant::canConvert(QMetaType) or QVariant::canConvert<T>()
* QMessageBox::standardIcon is deprecated, use QStyle::standardIcon()
* Replace deprecated method QMessageBox::question(), ...
* QApplication::fontMetrics() is deprecated
* QDropEvent::mouseButtons() is deprecated, use buttons()
* QDropEvent::keyboardModifiers() is deprecated, use modifiers()
* Constructor of QFontDatabase is deprecated, use static methods instead
* Qt::AA_DisableHighDpiScaling is deprecated
* Qt::AA_EnableHighDpiScaling is deprecated
* Qt::AA_UseHighDpiPixmaps is deprecated
The latter is intended for a specific solver constraint.
[Sketcher] Make further changes for tangent-at-knot separation
1. Remove code for tangent-at-knot from `addAngleAtPointConstraint`.
2. Use correct order of input.
3. Separate internal C0 knot vs end knots. The latter can still be constrained
but the user must use endpoints of the spline instead of knots.
Similar to 2715a66ff02a46f94ae3fc6527fd446e666b8e58.
Added some comments and removed some TODO's.
Return grad values directly rather than doing summation.
