- change some primitives into sub-primitives: fixnum+ fixnum- fixnum* inline-cache-miss inline-cache-miss-tail
- rename some relocation types for clarity
- some other minor re-organizations and cleanups
- new way to iterate over instruction_operands cleans up relocation code
- move some methods out of the VM class to clean up code
- if debugging is on, die earlier if attempting to allocate inside GC
- callback heap entries are now code_blocks
- replace block_granularity with data_alignment