Add Energy coloring

Add a button for “Energy coloring”

Colors from green to yellow to red mean low, middle and high energy. A red dot in it means “no bond”.

Strong second to this idea! (Colors may need a little tweaking as reds look too brown & red dots perhaps a bit too big & bright), but I love the idea! NIce visual, madde.

Of course the colors still need tweaking, we might even need two different energy ranges - one for “mini-loops” between two pairs and one for real loops. For those ones yellow and red should start at a higher energy level.