Compatibility

Type coercion consistency between "set [var] to [n]" and "change [var] by [n]"

In Scratch 2.0 if you set {var} to {var + 1} and the variable contains a string, you get 1. If you change {var} by {1} when the variable contains a string, you get NaN. In 3.0 both now have the same behavior and return 1.

"delete [i] from [list]" now uses Math.floor rather than Math.round

https://github.com/LLK/scratch-vm/issues/202