Rubberband properties

[m-kuhn]

Because it allows for nice effects. It also works with good looking colours.

QPropertyAnimation *animation = new QPropertyAnimation( mFeatureRubberband, "fillColor" );
connect( animation, &QPropertyAnimation::finished, animation, &QPropertyAnimation::deleteLater );
connect( animation, &QPropertyAnimation::valueChanged, this, [this]
{
  mFeatureRubberband->update();
} );

animation->setDuration( 2000 );
animation->setStartValue( QColor( 100, 255, 100, 255 ) );
animation->setEndValue( QColor( 100, 255, 100, 0 ) );

animation->start();

Like #7508