Dynamic dolly speed/rotation sensitivity

[keywizzle]

-Removed excess rotation after mouse is idle for >100ms

[trusktr]

@keywizzle a couple things we need for this PR:

• better description, describe what this does
• unit test to make sure we catch a regression in the math, namely because the math is a hard piece of code to understand (namely the one involving the perspective, which could break if someone updates how Scene.ts works)