Non-global `backBuffer`

[benjaminleonard]

I think having backBuffer defined as it is globally makes it shared between multiple programs running off the same textRenderer instance. The result being that the isSameCell check is almost always false.

const newCell = buffer[idx]
const oldCell = backBuffer[idx]
if (!isSameCell(newCell, oldCell)) {
  rowNeedsUpdate = true
  backBuffer[idx] = { ...newCell }
}

I've worked around this locally by adding a createRenderer function that contains the renderer – thereby creating a new backBuffer for each instance.