VOXEDIT: option to show the volumes in the world position in edit mode, too

[mgerhardy]

The struct RenderContext contains a boolean called sceneMode - this is most likely not enough here, as I currently implemented it in a way that you either want the transforms to be applied, or not - and I use this to determine either scene mode or edit mode.

If we now want this feature to become reality we would most likely have to

• update the mouse tracing (SceneManager::mouseRayTrace) to take the world position of the node into account
• maybe not making it a boolean but an enum with EditModeNoTransform, EditModeTransform, SceneMode