towards a 64 bit vm / image

I put together some patches that redo the pidgin type system to use
traits instead of rules, use sizeof instead of hard coded
bit/byte/word sizes, and write slate images based on a given bitsize
instead of assuming 32 bits. I'm doing this because i want to run
slate on my amd64 system. Unfortunately it's broken now and nothing
works, but hopefully I'll fix that in the next few years if I'm lucky.
It includes some other stuff I think.