Fix a couple of subtle bugs.
- the VM was conditionally reading from the instruction stream, so that
other bugs got masked by decoding errors.
- push-n-bytes was clobbering eax.
It was possible for an instruction to write out of bounds of the memory
data structure. Most of the time this worked fine. However if the block
ever got resized and moved the out-of-bounds bytes no longer went along.
Kartik Agaram
Maxwell Bernstein