MMB changes: ConvRef has been merged with Ref

[digama0]

Just a heads-up, the MMB format has changed to eliminate ConvRef. Ref should pop a conversion obligation if the heap element is a conversion.

kernel/src/stream/proof.rs

Lines 179 to 182 in 491ab31

	fn reference(&mut self, idx: u32) -> KResult {
	let i = self.proof_heap.get(idx).ok_or(Kind::InvalidHeapIndex)?;
	self.proof_stack.push(i);

Unfold also no longer pops three elements from the stack. See https://github.com/digama0/mm0/blob/master/mm0-c/mmb.md