Fill background layer

[Likbjorn]

Related to #25. Fill background with randomly generated non-interactable nodes for aesthetic purposes.

Nodes perform constant slow-paced movement. Nodes are small, transparent and blurred.

Links between nodes to be described later. Options:

• Delaunay triangulation
• Complete graph with distance-dependent opacity of links.

[Likbjorn]

Background layer is not needed anymore for two reasons:

• Bad for performance.
• Screen will be overloaded with objects.