Set marker color according to color used in threshold i.e. selected color when using MulticolorMarker
Instead of calculating the color of the marker, as is neccessary for the casern marker, we now choose the middle color of the subspace we search in. E.g. when we search for orange beanies, we just say that every found beanie is orange, without actually querying pixel values. This still works, since the detection itself is already color based.
This mitigates issues with e.g. the combined aruco- and multicolor-marker.
Closes #89 (closed)