`markForUpdate` method

[Y-Less]

Rather than sending updates to entities instantly, some would be better with a markorUpdate method that sends all the updates at once next tick. This is to combine them in to fewer packets when changing settings involves, say, recreating the entire entity. Currently if a script changes five settings at once that's five recreations when one will do.

This should be an internal function, not in the SDK (probably) as the packets are an implementation detail. The idea is inspired by the current need for setColourAndText to update two things at once.