This replaces VMMaker.oscog-dtl.2711 from the VMMaker inbox (9 February 2020), which I will move to treated.

I merged the original submission, made a few changes, and added one new primitive based on earlier suggestions on vm-dev.

This provides primitive support to allow the image to inform the VM that it can change the image format number from 68021 to 68533 after the image has been recompiled with SistaV1.

It also provides a primitive for querying the VM for supported bytecode sets, such that this will work:

Smalltalk supportedEncoders ==> {EncoderForV3 . EncoderForV3PlusClosures . EncoderForSistaV1}

I am attaching a change set that illustrates the use of the two primitives.

Dave