Next-gen compiler (experimental)

[IntegralPilot]

Rewrite of OOMIR to be much cleaner and SSA, as well as much nicer layout and code for the compiler. Been working on for a while, just uploaded as it's ready to share.

The diff size is comically large because I moved a bunch of files, it's not rly that much

Current status:

• Compile speed, depends on the crate but generally 2x-3x improvement (debug), 1.5-2x improvement (release) in my testing
• Memory usage (max RSS) - depends heavily on the crate, can range from basically the same (+/- 0.5%) to 2.5x improvement for some (large_methods went from 2472 to 991 MB)
• Runtime speed - currently a slight regression, this is what I need to fix before merging! SSA enables much better optimisation etc. so I think I can actually get this to an improvement

[IntegralPilot]

runtime speed has now caught up and I'm happy with it, so merging