Baystation holomaps break when opened repeatedly

[tontyGH]

Opening the holomap repeatedly eventually throws a runtime error and prevents you from opening the holomap again. The exception message mentions an invalid EntityID so I think it's might be a problem on the client's end

I had these PRs merged to my branch while testing, though it seems unrelated:

• Implements icon.DrawBox() #2659
• Refactors particles to allow multiple owners #2657
• Re-implement range() and orange() to match BYOND #2604
• Implements vis_flags #2624

[wixoaGit]

What's the runtime?

[tontyGH]

[tontyGH]

Knowing that ClientImagesList doesn't correctly implement ContainsValue, I'm inclined to believe it's related to this because of the OperatorCombine call.

[tontyGH]

Just checked, the issue seems to be two-fold. Implementing ContainsValue does fix the runtime, but the issue still persists.