Build with latest nightly (mostly)

I wanted to steal some code for my gameboy emulator but I realized that this code hadn't been updated in a while so I decided to give it a try.

Most of the breakage was due to changes in rust syntax (nampespaced enums, no automatic Copy etc...) however the audio interface to SDL2 seems to have changed quite a lot which means that the current code is completely broken.

In particular rust won't let me declare a static `AudioDevice` anymore because it implements Drop. I'm not sure how to fix that particular issue without rewriting a big chunk of code so I left it commented for now. If you have any clue what to do I can look into it some more.

But besides that it builds correctly with only one warning left that I can't quite figure out (it looks bogus to me but I might be missing something).

When I tried to run it with mario bros the game seemed very slow even though it wouldn't take all of my CPU, maybe there's a timing issue, I'm not sure (and since I never ran this emulator before I'm not sure how it's supposed to look like).

So, it's not finished but hopefully it'll be useful.