Quadratic movement in WorldsPlayer

let a = start position
let b = end position

p(t) = (b-a)t + a

let d = SetMove3Action's end point

p(t) = ((d-b)t+b)t + a = (dt - bt + b)t + a = (d-b)t^2 + bt + a

let d = 0, then p(t) = -bt^2 + bt + a

p'(t) = -2bt + b.

p'(t) = 0 when -2bt + b = 0, -2bt = -b, -2t = -1, t = 1/2

p(1/2) = 100

let a = 0 because we're actually working with offsets

100 = -bt^2 + bt

0 = -bt^2 + bt - 100
0 = bt^2 - bt + 100

0 = b(1/2)^2 - b(1/2) + 100
0 = b/4 - b/2 + 100
0 = b/4 - 2b/4 + 100
0 = -b/4 + 100
b/4 = 100
b = 400