Tweaks to molecular-bond interactive

Update labels, atom colors, graphs

[#74691454]
v2 of interactive: bouncing atoms and click-to-add 3rd

[#74691454]
Add initial bond-breaking model

[#74694358]
Disable components when model starts
Update forming bond interactive

* Draw m-w average energies
* Change text
* Update text on adding atom
* Add slow-mo checkbox
* Add forces checkbox

[#74691454]
Tweaks to breaking bond model

[#74694358]
Breaking bond tweaks

Move molecule position; rm mass slider; finer gradations 

[#74694358]
Breaking bonds position tweaks
Interactive tweaks.

Wording; layout; controls

[#74691454]
Merge branch 'chemical-reactions-energy-conservation'