This allows users to "map" (or "link") symbols with different names so that they can be compared without having to update either the target or base objects. Symbol mappings are persisted in objdiff.json, so generators will need to ensure that they're preserved when updating. (Example: https://github.com/encounter/dtk-template/commit/d1334bb79e71af1a7b3b090bffda4adc483f722c)
Resolves#117
No more scattered relocation handling and
feature checks. Everything will go through
the ObjArch trait, which makes it easier
to add new architectures going forward.