Merge indexArrays into one indexData array

[Louis-CharlesBiron]

more performant and scalable

const dataLength = 6
new indexData(arrSize*dataLength)

[i+0] = posX
[i+1] = posY
[i+2] = velX
[i+3] = velY
[i+4] = gravity
[i+5] = stepsAlive
[i+0] = etc