uh stupid me
not sure whether trolling or not

Just discovered that `val p1: VM @unboxed = p2` gets coerced into
`val p1: VM @unboxed = box2unbox(unbox2box(p2))`. Not sure whether that's
desired or not, but if yes, I've introduced a peephole optimization
that takes care of that stuff.
Merge pull request #19 from xeno-by/master

not sure whether trolling or not