Implement more of the roadmap

A few notes on implementing potential roadmap features. - It would be cool if inlined function were allowed. As a place to start, there is a short mention of inlining in [this post](https://blog.tartanllama.xyz/writing-a-linux-debugger-elf-dwarf/): "With inlining, for example, once we’ve found the function whose range contains our PC, we’ll need to recurse over the children of that DIE to see if there are any inlined functions which are a better match." - Add multi-word memory read and write using `process_vm_readv(2)`. The implementation would live in [`src/registers.c`](https://github.com/d4ckard/spray/blob/main/src/registers.c).