Since it was introduced, the `scale` parameter could be set to `true` to
enable dynamic scaling. In 57ca64e741bde04efb039c7d58adcdbf6693c61c, it was
modified to instead set a fixed scaling if it were set to a number, but this
didn't allow for a fixed scaling to be set on top of the dynamic scaling.

This change restores the original behavior of the `scale` parameter and moves
fixed scaling to a new `scaleFactor` parameter. This change breaks the
previous fixed scaling behavior, but this was never in a released version.