Message 79720 - Python tracker

@Paolo: I'm going to be looking into converting more common sequences
into superinstructions. We only have LOAD_CONST+XXX so far. The others
are difficult because vmgen doesn't provide easy ways to deal with error
handling, but Jakob and I have come up with a couple ideas to get around
that.

Replication would be trickier since we want the bytecode generation to
be deterministic, but it's probably doable too. I'll post any
significant results I get.