OpenGL specific extensions

box — Draw a bounding box around nodes.
axes — Defines methods to draw axes.
extInfos — give the capability to draw some information near each node.
scale — Draw an arrow with a label.
fogAndBGColor — Handle the background colour and the fog.
legend — Draw a frame with the representation of each atom species, its name and the number of elements.
marks — Draw features on nodes, like measurement marks or highlights.
rings — an extension to highlight closed rings in a structure.

New rendering facilities.