2. Post-generation fixups to work around bugs or project-specific stuff:

* Move `xdr.Operation` into a hidden namespace to avoid conflicts with the
  SDK's `Operation`.
* Minimize the diff by running `sed -ie s/\"/\'/g types/{curr,next}.d.ts`
  (because the generator uses a different prettier config--this could
  probably be fixed in the generator itself, but this is easy enough
  for now).
* Add workarounds:
  - `type Hash = Opaque[];` is a necessary alias that doesn't get gen'd
  - `Hyper` and `UnsignedHyper` need their signatures fixed because it
    should take a proper `Array` instead of a union'd `[]`
  - Some constants don't work correctly, ref. the linked issue

Account for generator bugs: constants that aren't present

Author: Shaptic